US Medical Glossary

Abdominal distension means the belly is visibly swollen, enlarged, or puffed out beyond its normal size. It may feel tight, uncomfortable, or painful. Causes range from harmless excess gas or constipation to more serious conditions such as ascites (fluid in the abdomen), bowel obstruction, ovarian cysts, enlarged liver or spleen, or abdominal tumors. Distension that comes on suddenly and is severe, is associated with inability to pass gas or have a bowel movement, is accompanied by fever and severe pain, or develops in someone with a history of liver disease or cancer should be evaluated urgently.

ICD-10: R14

Abdominal pain is discomfort or aching anywhere between the chest and the groin, often called a stomachache or belly pain. It can be crampy, sharp, dull, or burning, and may come and go or be constant. Common causes include gas, indigestion, constipation, menstrual cramps, gastritis, or food intolerance. More serious causes include appendicitis, gallstones, kidney stones, or an ulcer. Go to the emergency room if the pain is sudden and severe, accompanied by fever, vomiting blood, bloody stool, inability to pass gas, or a rigid abdomen, as these may indicate a medical emergency.

ICD-10: R10

The Affordable Care Act (ACA), signed into law in 2010, is the major US health reform legislation that expanded insurance coverage through multiple mechanisms: the Health Insurance Marketplace with income-based subsidies, Medicaid expansion in participating states, requirements for coverage of pre-existing conditions, prohibition on lifetime and annual benefit limits, extension of dependent coverage to age 26, and requirements for coverage of essential health benefits and preventive services without cost-sharing. The ACA significantly reduced the uninsured rate in the US.

Section 2709 of the Affordable Care Act requires most private health insurance plans to cover routine patient costs—such as doctor visits, lab tests, and imaging—when you participate in an approved clinical trial for cancer or another serious, life-threatening condition. Your insurer cannot drop you from coverage or reduce your benefits simply because you chose to enroll in a trial. This provision does not require plans to pay for the experimental treatment itself, but it does protect you from losing your regular health coverage while you seek cutting-edge care. Always verify that the trial is federally approved before assuming this protection applies.

ACE inhibitors (angiotensin-converting enzyme inhibitors) are medications that lower blood pressure by relaxing blood vessels. They block an enzyme that causes blood vessels to narrow, making it easier for the heart to pump blood. Common ACE inhibitors include lisinopril, enalapril, and ramipril. They are used for high blood pressure, heart failure, and diabetic kidney disease. A dry, persistent cough is a common side effect — if this bothers you, ask your doctor about switching to a related drug called an ARB. ACE inhibitors should not be taken during pregnancy. Avoid potassium supplements or salt substitutes unless your doctor approves.

Acid reflux occurs when stomach acid repeatedly flows back up into the esophagus, causing symptoms such as heartburn, regurgitation of sour liquid, chest discomfort, hoarseness, chronic cough, or a sensation of a lump in the throat. When acid reflux happens frequently and causes complications, the condition is called gastroesophageal reflux disease, or GERD. Risk factors include obesity, smoking, pregnancy, hiatal hernia, and certain medications. Lifestyle changes such as losing weight, avoiding trigger foods, eating smaller meals, and not lying down right after eating can help. Untreated GERD can damage the esophagus over time.

ICD-10: K21

Acne is a common skin condition that occurs when hair follicles become clogged with oil and dead skin cells. It causes pimples, blackheads, whiteheads, and sometimes deeper nodules or cysts, most often on the face, back, and chest. Acne affects people of all ages but is most common in teenagers due to hormonal changes. Severe or persistent acne can cause permanent scarring and emotional distress. Treatment options include topical retinoids, benzoyl peroxide, antibiotics, birth control pills for women, and isotretinoin (Accutane) for severe cases. Early treatment helps prevent scarring.

ICD-10: L70

Actuarial value is the percentage of total covered medical costs that a health plan pays for an average patient. If a plan has an actuarial value of 70%, the insurance company pays 70 cents of every dollar in covered expenses on average, and you pay the remaining 30% through deductibles, copays, and coinsurance. ACA marketplace plans are grouped into metal tiers based on actuarial value: Bronze (60%), Silver (70%), Gold (80%), and Platinum (90%). A higher actuarial value usually means higher monthly premiums but lower costs when you actually use care. Your individual experience may differ from the average depending on your health needs.

Acute bronchitis is a short-term inflammation of the bronchial tubes, which carry air to the lungs. It is most often caused by a viral infection such as a cold or flu. Symptoms include a persistent cough that may produce mucus, mild fever, chest discomfort, and fatigue. Most cases resolve on their own within two to three weeks. Antibiotics are usually not needed because viruses cause most cases. Treatment focuses on rest, staying hydrated, and using over-the-counter medications to relieve symptoms. Recurring episodes may indicate asthma or chronic bronchitis and should be evaluated by a doctor.

ICD-10: J20

Acute pain is pain that comes on suddenly and has a clear cause, such as an injury, surgery, or infection. It is typically sharp or intense and acts as a warning signal that the body has been harmed or is at risk. Acute pain is short-term—it usually lasts from a few minutes to about three months—and improves as the underlying cause heals. Common examples include a broken bone, a sprained ankle, or post-surgical pain. Acute pain is usually treated with rest, ice, compression, elevation, and pain medications. If acute pain does not improve within the expected timeframe, or grows worse, it may transition to chronic pain and requires further evaluation.

An adenoidectomy is surgery to remove the adenoids, glands located at the back of the nasal passage above the throat. Adenoids help fight infection in young children but can become enlarged, causing breathing problems, frequent ear infections, snoring, or sleep apnea. The surgery is done under general anesthesia and takes about 30 minutes. It is commonly performed in children, often alongside a tonsillectomy. Patients typically go home the same day. Recovery takes five to seven days. Mild nasal stuffiness and a sore throat are common after surgery. A soft diet and avoidance of strenuous activity are recommended during recovery to allow healing.

ADHD is a neurodevelopmental disorder characterized by persistent patterns of inattention, hyperactivity, and impulsivity that interfere with functioning or development. It is one of the most common childhood disorders and often continues into adulthood. There are three presentations: predominantly inattentive, predominantly hyperactive-impulsive, and combined. ADHD is not caused by bad parenting or lack of discipline — it has strong genetic and neurological roots. Treatment typically includes behavioral therapy, educational supports, and medication such as stimulants (methylphenidate, amphetamines) or non-stimulant alternatives.

ICD-10: F90

An adjustment is a change made to the original amount billed on a medical claim. Adjustments reduce what you owe and can occur for several reasons: your insurer negotiated a discount with your provider (called a contractual adjustment), a billing error was corrected, you qualified for financial assistance, or a duplicate charge was removed. Adjustments appear on your Explanation of Benefits as write-offs or contractual discounts. You should never be billed the full chargemaster rate if you have insurance—the adjustment between the billed charge and the allowed amount is what your provider agreed to waive. If you see a large balance, ask the billing office to itemize all adjustments that were applied.

The adrenal glands are two small, triangular glands — one sitting on top of each kidney — that produce hormones essential to life. The outer part, the adrenal cortex, produces cortisol — a stress hormone that helps regulate blood sugar, blood pressure, and the immune response — and aldosterone, which controls salt and water balance. The inner part, the adrenal medulla, produces adrenaline and noradrenaline — the hormones responsible for the fight-or-flight response. When the adrenal glands do not produce enough cortisol — a condition called Addison's disease — it can cause fatigue, low blood pressure, and weight loss. A tumor on the adrenal gland called a pheochromocytoma can cause dangerous spikes in blood pressure.

An advance directive is a legal document that states your wishes for medical treatment if you become unable to speak for yourself. It may include a living will (which describes treatments you do or do not want) and a healthcare proxy or durable power of attorney for healthcare (naming a trusted person to make decisions on your behalf). Completing an advance directive is important for all adults. Hospitals are required to ask about your advance directive upon admission. If you have one, bring a copy to the hospital. If you do not have one, hospital social workers can help you create one. It helps ensure your values guide your care.

An adverse drug reaction, or ADR, is any unwanted, harmful, or unexpected response to a medication taken at a normal therapeutic dose. ADRs differ from drug allergies in that most do not involve the immune system and can include side effects, toxic reactions from drug accumulation, or unexpected interactions between medications. Common examples include nausea from antibiotics, dizziness from blood pressure drugs, and muscle pain from cholesterol-lowering statins. Report ADRs to your doctor or pharmacist so the medication can be adjusted, substituted, or discontinued. Serious ADRs can also be reported directly to the FDA through the MedWatch safety reporting program.

An adverse event is any unexpected or harmful medical occurrence that happens during or after a medical treatment, drug therapy, or clinical trial—whether or not it is caused by the treatment itself. Examples include an unexpected drug side effect, an allergic reaction, a fall in the hospital, or a new symptom that develops during a study. Healthcare providers and clinical trial sponsors are required to report serious adverse events to the FDA and relevant oversight boards. If you experience an unexpected health problem during treatment, report it to your doctor immediately. You may also file a report with the FDA's MedWatch program. Adverse events can affect your insurance coverage if the event leads to additional medical care.

An air ambulance is emergency medical transport by helicopter or fixed-wing aircraft, typically used when ground transport is too slow or impractical due to distance or terrain. Air ambulance rides are extremely expensive—often $30,000 to $100,000 or more—and have historically been a major source of surprise billing. The No Surprises Act, which took effect in 2022, extended federal surprise billing protections to most air ambulance services, limiting your out-of-pocket cost to your in-network cost-sharing amount even if the air ambulance provider is out of network. However, coverage can still vary, so always check whether your plan covers emergency air transport and what your maximum exposure is.

Alcohol use disorder is a medical diagnosis given when drinking causes significant problems in a person's life or health, and the person has difficulty cutting back despite those problems. It exists on a spectrum from mild to severe. Symptoms include strong urges to drink, difficulty controlling how much you drink, withdrawal symptoms when not drinking, and drinking interfering with relationships, work, or daily activities. This is a treatable condition, not a character flaw. Treatment options in the US include medication (such as naltrexone or acamprosate), behavioral therapies, and peer support programs like SMART Recovery or Alcoholics Anonymous. Your doctor can guide you toward the best option.

ICD-10: F10

Allergy testing identifies which substances trigger an allergic reaction in your body. The two most common methods are skin-prick testing and blood testing. In a skin-prick test, a healthcare provider places tiny drops of common allergens (pollens, dust mites, pet dander, foods) on your forearm or back, then lightly pricks the skin through each drop. A raised, red bump (wheal) at a site within 15–20 minutes indicates an allergy. Blood tests (like RAST or ImmunoCAP) measure IgE antibodies specific to each allergen. Allergy testing guides treatment decisions such as avoidance strategies, antihistamine prescriptions, or allergen immunotherapy (allergy shots).

The allowed amount is the maximum dollar amount your insurance plan agrees to pay for a covered service or item. It is set by contract between your insurer and in-network providers. If your doctor charges more than the allowed amount, an in-network provider must write off the difference; you only owe your share (deductible, copay, or coinsurance) of the allowed amount. With out-of-network providers, you may owe the full difference between the billed charge and the allowed amount, called balance billing. You will see the allowed amount listed on your Explanation of Benefits (EOB).

Alopecia refers to hair loss, which can range from small, patchy bald spots (alopecia areata) to complete loss of all body hair (alopecia universalis). Alopecia areata is an autoimmune condition where the immune system mistakenly attacks hair follicles. Hair loss can also be caused by genetics (androgenetic alopecia), stress, nutritional deficiencies, thyroid disease, or certain medications. Treatment depends on the cause and may include corticosteroid injections, topical minoxidil, oral medications including JAK inhibitors, and hair transplant surgery in some cases. Some forms resolve on their own.

ICD-10: L63

Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, is a rapidly progressive neurodegenerative disease that attacks motor neurons controlling voluntary muscle movement. As motor neurons die, muscles weaken and waste away, eventually causing paralysis. Early symptoms include muscle twitching, cramping, slurred speech, and weakness in hands, feet, or legs. It affects breathing and swallowing as it progresses. Most people with ALS live 2 to 5 years after diagnosis, though some live much longer. While there is no cure, medications like riluzole and edaravone can modestly slow progression, and multidisciplinary supportive care helps maintain function and quality of life.

ICD-10: G12

Alveoli are the tiny, balloon-shaped air sacs at the very end of the airways inside your lungs. There are about 300 million of them in each lung, and together they provide a huge surface area — roughly the size of a tennis court — where oxygen from the air you breathe passes into your bloodstream, and carbon dioxide, a waste gas, passes out so you can exhale it. The walls of the alveoli are extremely thin, just one cell thick, to allow this gas exchange to happen quickly. Conditions like pneumonia, COVID-19, and emphysema can damage or fill the alveoli with fluid, making it hard to breathe and reducing the oxygen level in your blood.

Alzheimer's disease is a progressive brain disorder that slowly destroys memory, thinking skills, and the ability to carry out simple tasks. It is the most common cause of dementia in older adults. Abnormal protein deposits called amyloid plaques and tau tangles damage and kill brain cells over time. Early symptoms include forgetting recent events, getting lost in familiar places, and trouble with language. As it advances, people may not recognize family members or be able to care for themselves. There is no cure, but medications and supportive care can temporarily slow symptom progression.

ICD-10: G30

Ambulatory blood pressure monitoring records your blood pressure at regular intervals throughout a 24-hour period while you go about your normal day and sleep at night. A blood pressure cuff is wrapped around your upper arm and connected to a small recording device worn on a belt. The cuff automatically inflates and records a reading every 20 to 30 minutes during the day and every 30 to 60 minutes at night. You will be asked to keep a diary noting your activities and sleep times. The cuff may be mildly uncomfortable when it inflates, especially during sleep. ABPM is used to diagnose hypertension, white coat syndrome — high readings only in the doctor's office — and to evaluate whether blood pressure medications are working throughout the day.

Amniocentesis is a prenatal procedure in which a thin needle is inserted through the abdomen into the uterus to withdraw a small sample of amniotic fluid, which contains fetal cells. Ultrasound guidance is used throughout the procedure to direct the needle safely. You may feel pressure or a brief cramping sensation. The test is typically performed between 15 and 20 weeks of pregnancy. The fluid is sent to a laboratory where the fetal chromosomes are analyzed to detect conditions such as Down syndrome, spina bifida, or other chromosomal abnormalities. Results usually take one to two weeks. There is a small risk of miscarriage of less than one percent. Rest is recommended for the remainder of the day.

Amniotic fluid is the protective liquid that surrounds your baby inside the amniotic sac (the "bag of waters") during pregnancy. It cushions the baby, maintains temperature, supports lung development, and allows the baby to move freely. The amount is measured by ultrasound using the amniotic fluid index (AFI). Too little fluid (oligohydramnios) can cause cord compression and restrict fetal growth; too much (polyhydramnios) can cause preterm labor. When the sac ruptures (your water breaks), amniotic fluid leaks out — a clear, odorless fluid. If your water breaks before labor begins, you should contact your provider immediately.

ICD-10: O41

Amounts Generally Billed (AGB) is the maximum amount a nonprofit hospital may charge a patient who does not have insurance, under IRS Section 501(r) rules. The AGB is calculated using one of two IRS-approved methods: either based on what Medicare and all private insurers paid for the same services, or based solely on Medicare rates. This cap protects uninsured patients from being charged the hospital's full chargemaster list prices, which are far higher than what insured patients effectively pay. If you are uninsured or underinsured and receive a hospital bill that appears to exceed the AGB, ask the billing office to recalculate using your facility's AGB methodology and apply any eligible financial assistance.

Amputation is surgery to remove a limb or part of a limb, such as a finger, toe, foot, leg, arm, or hand. It is performed when a limb is severely damaged by injury, has poor circulation due to diabetes or vascular disease, or is affected by cancer or severe infection that cannot be controlled. The goal is to preserve as much function as possible and to prevent life-threatening spread of infection. Surgery is done under general or regional anesthesia. Recovery involves wound healing, pain management, and psychological support. Physical rehabilitation and prosthetic fitting are important parts of long-term recovery. Phantom limb sensations, where the missing limb still feels present, are common after amputation.

Analgesics are pain-relieving medications. They range from mild over-the-counter options like acetaminophen (Tylenol) and ibuprofen (Advil) to stronger prescription opioids. Different analgesics work in different ways — some reduce inflammation, others block pain signals in the brain. They are used for headaches, muscle aches, arthritis, post-surgical pain, and chronic conditions. Always follow dosing instructions carefully. Acetaminophen can damage the liver in high doses or with alcohol. Some analgesics can upset the stomach — taking them with food may help. Tell your doctor if your pain is not well controlled, as stronger options may be available.

Anemia is a condition in which the blood does not have enough healthy red blood cells to carry adequate oxygen to the body's tissues. Red blood cells contain hemoglobin, a protein that transports oxygen. When hemoglobin levels are too low, the body does not get the oxygen it needs. Common symptoms include fatigue, weakness, pale skin, shortness of breath, dizziness, and headaches. Anemia has many causes including iron deficiency, vitamin B12 deficiency, blood loss, chronic illness, and inherited conditions. Treatment depends on the underlying cause and may include dietary changes, supplements, or medical procedures.

ICD-10: D64

Anesthesia refers to medication used to prevent patients from feeling pain during surgery or other medical procedures. An anesthesiologist or certified registered nurse anesthetist (CRNA) administers and monitors anesthesia throughout the procedure. Types include general anesthesia (complete unconsciousness), regional anesthesia (numbing a large area of the body), and local anesthesia (numbing a small area). Sedation may also be used to help patients relax or sleep lightly during procedures. The type of anesthesia used depends on the procedure, the patient's health, and their preferences. Before surgery, the anesthesia team will review your medical history, medications, and allergies. You will be given instructions about fasting before the procedure to reduce aspiration risk.

Angina pectoris is chest pain or discomfort caused by reduced blood flow to the heart muscle. It is a symptom of coronary artery disease. The pain is often described as pressure, squeezing, heaviness, or tightness in the chest and may also be felt in the arms, neck, jaw, or back. Stable angina is triggered by physical activity or stress and goes away with rest or nitroglycerin. Unstable angina occurs at rest or with minimal activity and can signal an impending heart attack, requiring emergency evaluation. Treatment includes medications, lifestyle changes, and procedures to improve blood flow to the heart.

ICD-10: I20

An angiogram is an imaging test that uses X-rays and a contrast dye injected through a thin tube called a catheter to visualize blood vessels and check for blockages or abnormalities. The catheter is usually inserted into an artery in your groin or wrist. You will be awake but given a sedative to help you relax. A local anesthetic numbs the insertion site. The dye flows through your vessels, and X-ray images are taken in real time using fluoroscopy. The procedure typically takes one to three hours. Afterward, you must lie still for a period to allow the insertion site to heal. You may need to increase fluid intake to flush the contrast dye out through your kidneys.

Angioplasty is a minimally invasive procedure used to open narrowed or blocked arteries, most commonly coronary arteries that supply blood to the heart. A thin flexible tube called a catheter is threaded through a blood vessel, usually in the wrist or groin, to the blocked area. A small balloon at the tip is inflated to widen the artery, and a small mesh tube called a stent is often placed to keep it open. The procedure is performed under local anesthesia with sedation. Most patients go home within one to two days. You may need blood-thinning medications for a period after the procedure to prevent clotting.

Ankle swelling is the accumulation of fluid around the ankle joint, causing visible puffiness or tightness. Minor ankle swelling often results from prolonged standing or sitting, heat, or a mild sprain. More significant causes include venous insufficiency, pregnancy, heart or kidney failure, medication side effects such as calcium channel blockers or NSAIDs, and deep vein thrombosis (DVT). Call your doctor promptly if ankle swelling is sudden, affects only one side, is associated with pain or redness, or comes with shortness of breath or chest pain. Elevating the legs, reducing dietary salt, and wearing compression stockings often help relieve mild cases.

ICD-10: R60

Ankylosing spondylitis (AS) is a chronic inflammatory arthritis that primarily affects the spine and sacroiliac joints, causing pain and stiffness in the lower back and buttocks that is typically worse in the morning or after inactivity. Over time, inflammation can cause spinal vertebrae to fuse, leading to a hunched posture and reduced flexibility. It can also affect the hips, shoulders, eyes, and heart. It is more common in men and often begins in young adulthood. Treatment includes NSAIDs, biologic medications, physical therapy, and posture exercises to maintain spinal mobility and reduce pain.

ICD-10: M45

The Annual Notice of Change (ANOC) is a document Medicare Advantage and Medicare Part D plan members must receive each September, before the open enrollment period. It summarizes all plan changes taking effect January 1 of the coming year, including changes to premiums, deductibles, copays, drug formularies, covered benefits, and network providers. Reviewing this notice is critical so you can decide whether to stay in your current plan or switch during the October 15 to December 7 open enrollment window. If you do not receive your ANOC by late September, contact your plan directly to request one.

An annual wellness visit is a preventive healthcare appointment with a primary care provider focused on health maintenance rather than treatment of an existing condition. Under the ACA, covered plans must provide these visits at no cost when in-network. For Medicare beneficiaries, the Annual Wellness Visit (AWV) reviews health risk factors, updates a personalized prevention plan, and screens for cognitive impairment — distinct from the Welcome to Medicare visit for new enrollees. Combining a wellness visit with treatment of an active problem may result in a separate copay for the treatment portion.

Anti-anxiety medications help reduce symptoms of anxiety disorders such as excessive worry, panic attacks, and phobias. The most commonly prescribed class for quick relief is benzodiazepines (such as alprazolam and lorazepam), which calm the central nervous system but carry a risk of dependence and should only be used short-term. For long-term management, doctors often prescribe SSRIs, SNRIs, or buspirone, which are safer for ongoing use. Avoid alcohol and other sedatives while taking anti-anxiety medication. Do not stop benzodiazepines suddenly — taper under medical supervision. Therapy alongside medication is often the most effective approach.

Antibiotics are medicines that kill or stop the growth of bacteria. They are used to treat bacterial infections such as strep throat, urinary tract infections, and pneumonia. They do not work against viruses like the flu or common cold. It is important to take the full course even if you feel better early — stopping too soon can allow bacteria to come back stronger. Common side effects include stomach upset and diarrhea. Tell your doctor about any allergies you have. Some antibiotics interact with other medications, so always share your full medication list.

Anticoagulants, commonly called blood thinners, are medications that prevent blood clots from forming or growing. They are used to reduce the risk of stroke, heart attack, pulmonary embolism, and deep vein thrombosis. Common anticoagulants include warfarin (Coumadin), apixaban (Eliquis), rivaroxaban (Xarelto), and heparin. If you take warfarin, your blood levels (INR) need regular monitoring. Anticoagulants increase bleeding risk — report unusual bruising, prolonged bleeding, or blood in urine or stool. Avoid aspirin and NSAIDs unless directed. Inform all healthcare providers you are on a blood thinner before any procedure.

Anticonvulsants, also called antiepileptic drugs, are medications used to prevent or reduce seizures in people with epilepsy. They are also used for nerve pain, bipolar disorder, and migraine prevention. Common anticonvulsants include levetiracetam (Keppra), gabapentin, valproic acid, and lamotrigine. It is critical to take these medications consistently at the same time each day. Missing doses can trigger seizures. Do not stop anticonvulsants suddenly without your doctor's guidance. Blood levels are sometimes monitored to ensure therapeutic dosing. Some anticonvulsants interact with hormonal birth control, reducing its effectiveness — discuss this with your doctor or pharmacist.

Antidepressants are medications used to treat depression, anxiety, and other mental health conditions. They work by changing the balance of chemical messengers (neurotransmitters) in the brain, such as serotonin, norepinephrine, and dopamine. Common types include SSRIs (like sertraline and fluoxetine), SNRIs (like venlafaxine), and others. They typically take 2 to 6 weeks to show full effects — do not stop taking them just because you do not feel immediate improvement. Do not stop suddenly without consulting your doctor, as this can cause withdrawal symptoms. Some antidepressants interact with other medications. Tell your doctor about all supplements you take, especially St. John's Wort.

Antidiabetic medications are used to manage blood sugar levels in people with type 1 or type 2 diabetes. They work in different ways — some help the pancreas make more insulin, others make the body more sensitive to insulin, and some prevent the kidneys from reabsorbing sugar. Common types include metformin, sulfonylureas, GLP-1 agonists, SGLT-2 inhibitors, and insulin. Metformin is often the first medication prescribed for type 2 diabetes. Blood sugar monitoring is important to know if your medication is working. Watch for signs of low blood sugar (hypoglycemia) such as shakiness, sweating, or confusion, and always carry a fast-acting glucose source.

Antidiarrheal medications slow down bowel movements and reduce the frequency of loose stools. Common options include loperamide (Imodium), available over the counter, and bismuth subsalicylate (Pepto-Bismol). They are used for short-term diarrhea caused by infections, food intolerance, or travel. Loperamide slows gut motility; bismuth has mild antimicrobial properties. Staying well hydrated is essential during diarrhea to prevent dehydration — especially in children and older adults. Do not use antidiarrheals if diarrhea is caused by a bacterial infection with fever or bloody stool, as slowing the gut can worsen these conditions. See a doctor if diarrhea lasts more than two days.

Antiemetics are medications that prevent or treat nausea and vomiting. They work by blocking signals in the brain that trigger the nausea reflex. They are used during chemotherapy, surgery recovery, motion sickness, pregnancy (morning sickness), and gastroenteritis. Common antiemetics include ondansetron (Zofran), promethazine (Phenergan), metoclopramide (Reglan), and meclizine (Antivert). Ondansetron is often prescribed for nausea related to chemotherapy or surgery. Some antiemetics cause drowsiness — use caution with driving. For pregnancy-related nausea, always discuss medication options with your obstetrician before taking anything, even over-the-counter options.

Antifungals are medicines used to treat infections caused by fungi. Common fungal infections include athlete's foot, ringworm, yeast infections, and thrush. Antifungals come as creams, powders, pills, or IV infusions depending on the type and severity of infection. Mild skin infections are often treated with over-the-counter topical creams, while serious internal infections may require prescription oral or IV treatment for weeks or months. It is important to complete the full course of treatment. Some oral antifungals can interact with other medications or affect the liver, so periodic blood tests may be needed.

Antihistamines block histamine, a chemical the body releases during an allergic reaction. They relieve symptoms like sneezing, runny nose, itchy eyes, hives, and allergic skin reactions. They are also used to treat motion sickness and help with sleep. First-generation antihistamines (like diphenhydramine, found in Benadryl) cause drowsiness and are best taken at night. Second-generation antihistamines (like cetirizine, loratadine, and fexofenadine) cause less drowsiness and are suitable for daytime use. Avoid alcohol while taking antihistamines. Older adults should use antihistamines with caution due to increased risk of confusion and falls from sedating effects.

Antihypertensives are medications used to lower high blood pressure (hypertension). Uncontrolled high blood pressure can lead to heart attack, stroke, and kidney damage. There are several types, including ACE inhibitors, beta-blockers, calcium channel blockers, and diuretics. Your doctor may prescribe one or a combination. Most people take these medications every day for life. Do not stop taking them without talking to your doctor, even if you feel fine — blood pressure often has no symptoms. Monitor your blood pressure at home if possible. Lifestyle changes like reducing salt intake, exercising, and limiting alcohol also help control blood pressure.

Antipsychotics are medications used to manage symptoms of psychosis, including hallucinations, delusions, and disordered thinking. They are commonly prescribed for schizophrenia, bipolar disorder, and severe depression. Older (first-generation) antipsychotics include haloperidol; newer (second-generation) ones include risperidone, quetiapine, and aripiprazole. Side effects can include drowsiness, weight gain, and metabolic changes. Some antipsychotics can cause movement-related side effects such as restlessness or stiffness. Regular follow-up with your doctor is important to monitor effectiveness and side effects. Do not stop taking antipsychotics without medical guidance, even if you feel well.

Antivirals are medications that fight viral infections by slowing or stopping the virus from multiplying in the body. They are used to treat conditions like influenza, herpes, HIV, hepatitis B and C, and COVID-19. Unlike antibiotics, they do not cure the infection but help control symptoms and reduce complications. Starting antiviral treatment early — often within the first 48 hours of symptoms — is important for best results. Some antivirals are taken as daily long-term therapy. Side effects vary by drug but may include nausea, headache, or fatigue. Never share antiviral medications with others.

Anxiety disorders are a group of conditions in which worry, fear, or nervousness is intense, persistent, and interferes with everyday activities. Unlike normal stress, anxiety disorders do not go away on their own and can worsen without treatment. Symptoms may include racing heart, sweating, trouble sleeping, avoidance of situations, and difficulty concentrating. Several types exist, including generalized anxiety disorder, panic disorder, social anxiety disorder, and specific phobias. Anxiety disorders are among the most common mental health conditions in the US and respond well to therapy, medication, or both. Your primary care doctor can provide a first assessment or refer you to a specialist.

ICD-10: F41

The aorta is the largest artery in the body, about the width of a garden hose. It starts at the top of the heart's left ventricle, arches up through the chest, and then runs down through the abdomen before splitting into smaller arteries that supply the legs. The heart pumps oxygen-rich blood into the aorta with every heartbeat, and from there it is distributed to the rest of the body. An aortic aneurysm is a bulge or weakening in the aorta's wall that can be life-threatening if it ruptures. High blood pressure puts extra strain on the aorta over time, which is one reason controlling your blood pressure matters so much.

An aortic aneurysm is an abnormal bulge in the wall of the aorta, the body's largest artery that carries blood from the heart to the rest of the body. The bulge forms when the aortic wall weakens. Aneurysms can occur in the chest (thoracic) or abdomen (abdominal aortic aneurysm). Most cause no symptoms and are found incidentally on imaging. However, if the aneurysm ruptures it can cause sudden, severe pain and life-threatening internal bleeding. Risk factors include smoking, hypertension, high cholesterol, and family history. Treatment depends on size and may include monitoring, medications, or surgery to repair the aneurysm.

ICD-10: I71

The aortic valve is a one-way gate between the heart's left ventricle — the main pumping chamber — and the aorta, the largest artery in the body. It has three leaflets, or cusps, that open with each heartbeat to let oxygen-rich blood rush into the aorta and snap shut to stop blood from flowing back into the heart. When the valve stiffens and narrows with age — a condition called aortic stenosis — the heart has to work much harder to push blood through, causing fatigue and chest pain. When it does not close tightly and blood leaks back — aortic regurgitation — the heart can become overworked. Both problems can be treated with valve replacement surgery or a catheter-based procedure called TAVR.

The Apgar score is a quick health check given to your newborn at 1 minute and 5 minutes after birth. Five signs are each scored 0 to 2: Appearance (skin color), Pulse (heart rate), Grimace (reflex response), Activity (muscle tone), and Respiration (breathing effort). Scores from 7 to 10 mean the baby is doing well. Scores below 7 at 5 minutes may mean the baby needs extra medical help such as extra oxygen. The Apgar score is not meant to predict long-term health outcomes; it guides immediate care decisions in the delivery room. Most healthy babies score 7 to 9.

An appeal is a formal request asking your health insurance company, employer health plan, or government program to reverse a decision to deny, reduce, or end coverage for a medical service, claim, or prescription. Federal law gives you the right to at least one internal appeal (reviewed by your insurer) and, if that fails, an independent external review by a third party. You must usually file an internal appeal within 180 days of receiving a denial notice. For urgent situations, you may request an expedited appeal, which must be decided within 72 hours. Keep copies of all documents and submit your appeal in writing. If the external reviewer rules in your favor, your insurer is legally required to comply.

The appeals process is the formal procedure for challenging an insurance company's denial of a claim or a request for coverage. If your insurer denies payment for a service or medication, you have the right to appeal. There are typically two levels: an internal appeal reviewed by the insurer and an external appeal reviewed by an independent organization. You generally have 180 days from receiving a denial to file an internal appeal. Time limits for the insurer to respond vary. The ACA requires all non-grandfathered health plans to provide these rights. Keeping records of all communications is important throughout the process.

An appendectomy is surgical removal of the appendix, a small pouch attached to the large intestine. It is most commonly performed as an emergency when the appendix becomes inflamed or infected, a condition called appendicitis. Without treatment, a ruptured appendix can be life-threatening. The surgery is usually done laparoscopically through small incisions using a tiny camera, though open surgery may be needed if the appendix has burst. Most patients go home within one to two days and return to normal activity within two to four weeks. Pain, bloating, and fever before surgery are typical warning signs.

Appendicitis is inflammation of the appendix, a small finger-shaped pouch attached to the large intestine in the lower right abdomen. It typically causes pain that starts around the navel and then moves to the lower right abdomen, often accompanied by nausea, vomiting, loss of appetite, and fever. Appendicitis is a surgical emergency because a ruptured appendix can cause a life-threatening infection called peritonitis. Treatment is usually surgical removal of the appendix, called an appendectomy. In selected mild cases, antibiotics alone may be considered. Prompt evaluation in an emergency room is essential when appendicitis is suspected, as early treatment leads to better outcomes.

ICD-10: K35

The appendix is a small, finger-shaped pouch about three to four inches long that hangs off the lower right side of the large intestine where the cecum begins. Its exact function in adults is not fully understood, though it may play a small role in the immune system early in life. Appendicitis — inflammation of the appendix, usually caused by a blockage — is one of the most common causes of emergency abdominal surgery in the United States. Symptoms include pain that starts around the navel and moves to the lower right abdomen, fever, nausea, and vomiting. Treatment is usually surgical removal — a procedure called an appendectomy — often done laparoscopically through small incisions.

An Applicable Large Employer (ALE) is a business or organization that employed an average of 50 or more full-time equivalent workers during the prior calendar year. Under the ACA's employer shared-responsibility provisions, ALEs must offer affordable, minimum-value health coverage to their full-time employees and their dependents, or face potential IRS penalties. Coverage is considered affordable if the employee's share of the premium for self-only coverage does not exceed a set percentage of their household income. If your employer has 50 or more employees and does not offer qualifying health insurance, you may be eligible to purchase subsidized coverage through the ACA marketplace. ALEs also file annual IRS reports (Forms 1094-C and 1095-C) to prove compliance.

Under the federal Emergency Medical Treatment and Labor Act (EMTALA), an appropriate transfer is the legally defined process by which a hospital may move an unstabilized emergency patient to another facility. For a transfer to be considered appropriate, the sending hospital must provide all medical treatment within its capacity to minimize risks of transfer, the receiving facility must have room and qualified staff to treat the patient, the receiving hospital must agree to accept the patient, and the patient (or their representative) must consent or the physician must certify that the benefits outweigh the risks. All relevant medical records must be sent along. Hospitals that violate appropriate transfer rules can face significant fines and loss of Medicare participation.

The Advanced Premium Tax Credit (APTC) is a federal subsidy that helps eligible individuals and families pay for health insurance purchased through the Marketplace. Eligibility is based on household income as a percentage of the federal poverty level and filing status. The credit can be applied in advance to monthly premiums, reducing what you pay each month, or claimed as a credit at tax filing. Income changes during the year should be reported promptly to avoid repayment at tax time.

An arrhythmia is an abnormal heart rhythm where the heart beats too fast, too slow, or irregularly. The heart's electrical system normally keeps the heart beating in a steady rhythm. When the electrical signals are disrupted, the heart may not pump blood efficiently. Some arrhythmias are harmless, while others can be life-threatening. Symptoms include palpitations, fluttering in the chest, dizziness, fainting, and shortness of breath. Common types include atrial fibrillation, ventricular tachycardia, and bradycardia. Treatment depends on the type and severity and may include medications, lifestyle changes, cardioversion, ablation, or an implantable device such as a pacemaker.

ICD-10: I49

An arterial blood gas (ABG) test measures the levels of oxygen, carbon dioxide, and pH in blood drawn directly from an artery — usually the radial artery in your wrist. Unlike routine blood draws from a vein, the ABG provides a real-time picture of how well your lungs are exchanging gases and whether your blood is too acidic or too alkaline. Results are available within minutes. Doctors order ABGs in emergency settings for patients with breathing difficulties, severe asthma, COPD exacerbations, overdoses, or after major surgeries. The draw is more uncomfortable than a regular blood draw and may cause brief sharp pain or bruising at the wrist.

Assignment of benefits is your written permission allowing your insurance company to pay your provider directly instead of sending reimbursement to you. When you sign an assignment of benefits form at a doctor's office, the payment goes straight to the provider. Without this assignment, the insurer would pay you, and you would then owe the full amount to your provider. Most in-network providers require assignment of benefits. It reduces paperwork for patients and ensures providers are paid promptly. Always check that you signed this form if you receive an unexpected payment check from your insurer.

Asthma is a chronic lung condition where the airways become inflamed and narrow, making it hard to breathe. It is triggered by allergens, exercise, cold air, smoke, or respiratory infections. Common symptoms include wheezing, chest tightness, shortness of breath, and coughing, especially at night or in the morning. Treatment includes quick-relief inhalers such as albuterol for sudden attacks and long-term controller medications such as inhaled corticosteroids to reduce inflammation. Most people with asthma can live active lives with a proper management plan developed with their doctor.

ICD-10: J45

Atrial fibrillation (AFib) is an irregular and often rapid heart rhythm that begins in the upper chambers of the heart. Instead of beating in a coordinated way, the upper chambers quiver chaotically. This can cause blood to pool and form clots, which may travel to the brain and cause a stroke. Symptoms include palpitations, shortness of breath, fatigue, and dizziness, though some people have no symptoms at all. Risk factors include age, high blood pressure, and heart disease. Treatment includes blood thinners to prevent stroke, medications to control heart rate, and procedures such as cardioversion or ablation.

ICD-10: I48

The heart has four chambers, and the atria are the two upper chambers — the right atrium and the left atrium. The right atrium receives oxygen-poor blood returning from the body through large veins and passes it down to the right ventricle, which pumps it to the lungs. The left atrium receives oxygen-rich blood returning from the lungs and passes it down to the left ventricle, which pumps it to the rest of the body. The atria contract just before the ventricles to help fill them with blood. Atrial fibrillation — often called AFib — is a common condition where the atria beat chaotically, which raises the risk of blood clots and stroke.

The auditory nerve, also called the vestibulocochlear nerve or the eighth cranial nerve, carries sound and balance information from the inner ear to the brain. It has two divisions: the cochlear nerve, which transmits hearing signals from the cochlea, and the vestibular nerve, which sends balance signals from the inner ear's balance organs. Sound vibrations converted into electrical signals by the cochlea's hair cells travel up the cochlear nerve to the brain's auditory processing areas. Conditions that damage the auditory nerve — such as acoustic neuroma (a benign tumor on the nerve), viral infections, or certain toxic medications — can cause one-sided hearing loss, tinnitus (ringing in the ears), or dizziness.

Authorization (also called prior authorization or precertification) is formal approval from your insurance plan before you receive certain medical services, procedures, or medications. Your doctor or hospital typically requests authorization by submitting clinical information to your insurer. Without authorization for services that require it, your plan may deny the claim or pay a reduced amount, leaving you with higher costs. Emergency care generally does not require prior authorization. Common services requiring authorization include specialist visits, surgeries, MRIs, brand-name drugs, and inpatient stays. Always confirm authorization status before a scheduled procedure.

An authorized representative is a person you formally designate to act on your behalf when dealing with your health insurance company or a government health program such as Medicare or Medicaid. This could be a family member, trusted friend, patient advocate, or attorney. Your representative can file claims, submit appeals, receive information about your coverage, and communicate with your insurer—all with the same legal authority as you. To designate someone, you typically need to complete a written authorization form provided by your insurer or plan. In Medicare, this is sometimes called an appointed representative. Having an authorized representative is especially important if you are seriously ill, have a disability, or speak limited English.

Autism screening is a brief developmental questionnaire given to parents at the 18-month and 24-month well-child visits to identify early signs of autism spectrum disorder (ASD). The most commonly used tool is the M-CHAT-R (Modified Checklist for Autism in Toddlers, Revised). Early signs include not making eye contact, not responding to their name, not pointing or waving, limited babbling or speech, and repetitive behaviors. Screening does not diagnose autism — a positive screen leads to further developmental evaluation. Early diagnosis allows access to early intervention therapies (such as speech, occupational, and applied behavior analysis) that can significantly improve outcomes.

ICD-10: F84

Autism spectrum disorder (ASD) is a neurodevelopmental condition that affects social communication, behavior, and sensory processing in ways that vary widely between individuals. It is called a spectrum because symptoms range from mild to severe. Signs often appear before age 3 and may include delayed speech, difficulty with social interactions, repetitive behaviors, and intense interest in specific topics. ASD is not caused by vaccines. Early diagnosis and intervention, including behavioral therapy, speech therapy, and educational support, can significantly improve outcomes. Every person with autism has unique strengths and challenges.

ICD-10: F84

Back pain is discomfort anywhere along the spine or the muscles of the back, from the neck down to the tailbone. It may feel like a dull ache, sharp stab, or burning sensation. Common causes include muscle strain, poor posture, a herniated disc, or arthritis. It can also result from a kidney infection or, rarely, a serious spinal condition. Most back pain improves with rest, over-the-counter pain relievers, and gentle movement. See a provider if the pain is severe, follows an injury, spreads down your leg, or comes with numbness, weakness, or bladder/bowel problems.

ICD-10: M54

Bad breath, or halitosis, is an unpleasant odor coming from the mouth that can be persistent or occasional. The most common cause is poor oral hygiene allowing bacteria to accumulate on the tongue, teeth, and gums. Other causes include gum disease, dry mouth, tooth infections, strongly flavored foods, tobacco use, and sinusitis. Medical conditions such as gastroesophageal reflux disease, kidney failure, liver disease, and uncontrolled diabetes can also cause distinctive breath odors. Persistent bad breath despite good oral hygiene should be evaluated by a dentist and possibly a doctor to rule out an underlying systemic or dental condition requiring treatment.

Balance billing happens when an out-of-network provider charges you the difference between what your insurer paid and the provider's full billed amount. For example, if a surgeon charges $5,000, your insurer pays $3,000, and the provider bills you the remaining $2,000 balance, that is balance billing. This can result in unexpectedly large bills. In-network providers typically cannot balance bill you because they have agreed to accept the insurer's allowed amount. Federal and state laws now limit balance billing in many situations, especially for emergency care.

Balance problems occur when you have difficulty maintaining your body's equilibrium while standing, walking, or moving. You may feel unsteady, wobbly, or as though you might fall. The balance system depends on the inner ear, vision, and the nervous system working together. Causes include inner ear disorders such as BPPV and Meniere's disease, peripheral neuropathy, medication side effects, low blood pressure, head injuries, and neurological conditions including Parkinson's disease and stroke. Sudden balance loss with dizziness, slurred speech, or weakness needs emergency evaluation — call 911. Recurrent balance problems raise fall risk; tell your doctor so they can assess the cause and recommend physical therapy.

ICD-10: R42

A basic metabolic panel (BMP) is a blood test that checks eight key substances in your blood. It measures sodium, potassium, calcium, bicarbonate, chloride, blood glucose, blood urea nitrogen (BUN), and creatinine. These values tell your doctor how well your kidneys are working, whether your electrolytes are balanced, and whether your blood sugar is in a healthy range. A nurse or technician draws blood from a vein in your arm. Doctors commonly order a BMP during routine checkups, hospital stays, or to monitor conditions like diabetes, kidney disease, or high blood pressure.

Behavioral health is a broad term used in the US healthcare system to encompass mental health conditions, substance use disorders, and the relationship between behavior and overall physical and mental wellbeing. It includes services such as psychotherapy, psychiatric medication management, substance use treatment, crisis intervention, and prevention programs. Many insurance plans use the term 'behavioral health' on insurance cards, EOBs, and provider directories to refer to mental health and addiction services. Behavioral health is increasingly integrated into primary care settings in the US, meaning you may be able to access a behavioral health provider directly at your doctor's office. Check your insurance card or provider directory for your plan's behavioral health benefits.

Belching, also called burping, is the release of gas from the stomach or esophagus through the mouth, typically accompanied by a sound. Occasional belching after eating or drinking is completely normal and helps relieve pressure in the stomach. Excessive or frequent belching that is disruptive can be caused by swallowing air, eating too quickly, carbonated beverages, or underlying conditions such as acid reflux, gastritis, peptic ulcer, or gastroparesis. If belching is accompanied by abdominal pain, bloating, nausea, or regurgitation of food, a medical evaluation is appropriate to rule out a gastrointestinal condition.

ICD-10: R14

Bell's palsy is a sudden, temporary weakness or paralysis of the muscles on one side of the face caused by inflammation or dysfunction of the facial nerve. It results in drooping of one side of the face, difficulty closing the eye, drooling, and changes in taste. The exact cause is unclear but is linked to viral infections such as herpes simplex. Symptoms typically appear abruptly and peak within 48 to 72 hours. Most people recover fully within weeks to months. Treatment usually includes a short course of corticosteroids and antiviral medications to speed recovery, along with eye protection.

ICD-10: G51

See EOB — Explanation of Benefits. The benefits summary, or EOB, is the document your insurer sends after processing a claim. It is not a bill but shows what was charged, what the insurer paid, any negotiated discounts, and your remaining financial responsibility. Reviewing the EOB against your provider's bill is essential for catching errors. Discrepancies should be reported to both the insurer and the provider. EOBs also show how much of your deductible and out-of-pocket maximum you have used for the year.

Beta-blockers are medications that slow the heart rate and reduce the force of heart contractions by blocking adrenaline effects. They are used to treat high blood pressure, heart failure, chest pain (angina), irregular heart rhythms, and anxiety. Common beta-blockers include metoprolol, atenolol, and carvedilol. Side effects may include fatigue, cold hands and feet, and dizziness. Do not stop beta-blockers suddenly — this can cause a dangerous rebound increase in heart rate and blood pressure. Tell your doctor if you have asthma or breathing problems before starting, as some beta-blockers can worsen lung conditions.

The bile duct is a small tube that carries bile — a digestive fluid that helps break down fats — from the liver and gallbladder into the first part of the small intestine called the duodenum. The common bile duct is formed when the duct from the gallbladder joins the duct from the liver. Bile travels down this duct after a meal and enters the small intestine through a small opening called the ampulla of Vater. When a gallstone, tumor, or other blockage obstructs the bile duct, bile cannot drain properly and backs up into the liver, causing jaundice — a yellowing of the skin and eyes. Doctors can examine the bile duct with a procedure called ERCP and place a stent to keep it open.

A billable code is a diagnosis or procedure code that is sufficiently specific to be submitted on a medical insurance claim. In ICD-10-CM, a billable code is a leaf node in the code hierarchy — it cannot be subdivided further. For example, J06.9 (Acute upper respiratory infection, unspecified) is billable, while J06 (Acute upper respiratory infections of multiple and unspecified sites) is a non-billable header. Using a non-billable code on a claim will result in claim rejection.

A binding decision is a final ruling issued by an independent external review organization or an arbitrator that your insurance company is legally required to follow. After you exhaust your insurer's internal appeal process, you have the right to request an external review by an Independent Review Organization (IRO). If the IRO rules in your favor, the insurer must cover the denied service—it cannot ignore or override the decision. Binding decisions are also issued in arbitration proceedings under the No Surprises Act for payment disputes between providers and insurers. Understanding that external review outcomes are binding gives patients a powerful tool to challenge wrongful denials without going to court.

A biologic is a type of prescription medication made from or derived from living cells—such as proteins, antibodies, genes, or tissues—rather than synthesized chemically. Biologics are used to treat complex conditions including rheumatoid arthritis, Crohn's disease, psoriasis, multiple sclerosis, and many cancers. Because they are difficult and expensive to manufacture, biologics are among the most costly drugs on the market. Insurance plans often place them on the highest formulary tier, requiring prior authorization, step therapy, or specialty pharmacy routing. Lower-cost versions called biosimilars have been approved by the FDA as safe alternatives. If you are prescribed a biologic, ask your doctor whether a biosimilar is available and whether copay assistance programs or manufacturer patient assistance programs can reduce your cost.

Biologic medications are complex drugs derived from living cells — such as bacteria, yeast, or mammalian cells — rather than manufactured through chemical synthesis. They include monoclonal antibodies, proteins, and gene therapies. Biologics are used to treat autoimmune diseases (like rheumatoid arthritis, Crohn's disease, and psoriasis), cancer, diabetes (insulin), and more. Because they target specific parts of the immune system, they can be very effective but also increase infection risk. Most biologics are given by injection or infusion and require refrigeration. Biosimilars are lower-cost versions approved as highly similar to an original biologic. Prior authorization from insurance is commonly required due to high cost.

A biopsy is a procedure in which a doctor removes a small piece of tissue or cells from your body so a pathologist can examine it under a microscope. Biopsies are used to diagnose cancer, infections, inflammatory diseases, and other conditions that cannot be confirmed by blood tests or imaging alone. The method varies by location: a needle biopsy uses a hollow needle to extract tissue, an incisional biopsy removes part of an abnormal area, and an excisional biopsy removes the entire area. Local anesthesia is usually given to numb the site. Results typically take several days to a week. A biopsy provides the most definitive diagnosis available.

A biopsy is a medical procedure in which a small sample of tissue or cells is removed from the body and examined under a microscope by a pathologist to diagnose or rule out disease, most commonly cancer. Types include needle biopsy, punch biopsy, endoscopic biopsy, and surgical excision biopsy. The method used depends on the location and suspected condition. Local anesthesia is usually applied to minimize discomfort. Biopsies may be performed in a clinic, radiology suite, or operating room. Results typically take several days and are used to guide treatment decisions. A biopsy is often the definitive step in confirming a diagnosis.

A biosimilar is a medication that is highly similar to an already approved biological drug, called the reference product, with no clinically meaningful differences in safety or effectiveness. Biologics are complex medicines made from living cells, including proteins, antibodies, and hormones used to treat conditions like rheumatoid arthritis, cancer, or inflammatory bowel disease. When a reference biologic's patent expires, other manufacturers can develop biosimilars that are generally less expensive. The FDA reviews biosimilars rigorously. Some biosimilars are designated interchangeable, meaning a pharmacist can substitute the biosimilar for the reference product without a new prescription from your doctor, similar to how generic drugs substitute for brand-name small-molecule drugs.

Bipolar disorder is a brain condition that causes unusual shifts in mood, energy, activity levels, concentration, and the ability to carry out everyday tasks. People with bipolar disorder experience episodes of mania or hypomania — periods of unusually high energy, reduced sleep, impulsivity, and elevated mood — as well as depressive episodes. These mood cycles vary in frequency and severity between individuals. Bipolar disorder is a lifelong condition but is very manageable with the right treatment plan, which typically includes mood-stabilizing medications, therapy, and consistent follow-up care. Early diagnosis and a strong support system significantly improve quality of life. Talk to a psychiatrist for an evaluation.

ICD-10: F31

A black-box warning, also called a boxed warning, is the FDA's strongest safety alert for a prescription drug. It appears surrounded by a bold black border at the top of the drug's official prescribing information and medication guide. The warning highlights serious or life-threatening risks, such as an increased risk of suicidal thoughts, severe liver damage, or dangerous interactions with other drugs. When your doctor prescribes a medication carrying this warning, they have weighed the serious risks against the expected benefits for your specific situation. Ask your doctor and pharmacist to explain the warning, what symptoms to watch for, and when to seek emergency care.

Black, tarry stools — medically called melena — are dark, sticky, and foul-smelling and indicate the presence of digested blood in the digestive tract. This is usually a sign of bleeding in the upper gastrointestinal tract, such as from a stomach ulcer, esophageal varices, or a Mallory-Weiss tear. It is a serious symptom that requires prompt medical evaluation. Iron supplements or bismuth-containing medications like Pepto-Bismol can also produce dark or black stools, so it is important to inform your doctor about any medications you take. True melena should be distinguished from dark stools caused by diet or supplements.

ICD-10: K92

The bladder is a hollow, muscular organ in your lower abdomen that stores urine produced by the kidneys. When full, it stretches to hold roughly one to two cups of urine. When you urinate, the muscles of the bladder wall contract and push urine out through the urethra. Common bladder problems include urinary tract infections, which cause burning and frequent urination, overactive bladder, incontinence (leaking urine), and bladder stones or tumors. If you notice blood in your urine, pain when urinating, or frequent urgent trips to the bathroom, you should let your doctor know. A urinalysis and imaging can help diagnose bladder conditions.

Bladder cancer is a malignant tumor that begins in the cells lining the bladder, the organ that stores urine. The most common symptom is blood in the urine, which may appear pink, red, or brown. Smoking is the leading risk factor. Other risk factors include exposure to certain chemicals and chronic bladder irritation. Treatment depends on the stage and may include surgery to remove tumors, BCG therapy (a form of immunotherapy placed in the bladder), chemotherapy, or radiation. Bladder cancer has a high recurrence rate, so regular follow-up is important.

ICD-10: C67

Bleeding gums refers to blood coming from the gum tissue, most commonly noticed when brushing or flossing. The most common cause is gingivitis, an early form of gum disease caused by plaque buildup. With proper dental hygiene, gingivitis and its associated bleeding can be reversed. Other causes include vitamin C or K deficiency, blood-thinning medications, bleeding disorders, leukemia, and hormonal changes during pregnancy. Persistent or heavy gum bleeding, or bleeding that occurs without brushing, should be evaluated by a dentist or doctor. Good oral hygiene, regular dental visits, and treating any underlying conditions are essential.

Bloating is the uncomfortable feeling that your abdomen is full, tight, or swollen. It is often accompanied by visible distension of the belly and may include gurgling sounds, cramping, or the passing of gas. Common causes include excess gas from swallowed air or gas-producing foods, constipation, irritable bowel syndrome, lactose intolerance, celiac disease, and overeating. Bloating that comes on suddenly and is severe, persists for more than a few days without relief, or is accompanied by significant pain, vomiting, or unexplained weight loss should be evaluated by a healthcare provider.

ICD-10: R14

A blood alcohol level test, often called a BAC (blood alcohol concentration) test, measures the amount of alcohol in your bloodstream. A nurse or technician draws blood from a vein in your arm. Results are expressed as a percentage; in the United States, a BAC of 0.08% or higher is the legal limit for driving in all states. The test is ordered in emergency rooms after accidents, overdoses, or suspected alcohol poisoning, and is used in legal and forensic settings. Blood alcohol peaks about 30–90 minutes after drinking and declines as the liver metabolizes it. A breathalyzer test is a non-invasive alternative commonly used by law enforcement.

A blood culture is a test that detects bacteria, fungi, or other organisms in your bloodstream — a condition called bacteremia or sepsis when the infection is serious. A nurse draws blood from a vein in your arm under very clean conditions and injects it into special bottles that encourage any organisms to grow. The laboratory monitors the bottles for up to five days. If organisms grow, lab scientists identify them and test which antibiotics kill them. This test is often ordered in hospital emergency or urgent-care settings when a patient has high fever, chills, low blood pressure, or other signs of a serious systemic infection.

Blood in the stool can appear as bright red blood on the toilet paper or in the bowl, or as dark red blood mixed into the stool. It should never be ignored. Bright red blood usually comes from the lower digestive tract such as hemorrhoids, anal fissures, or colon polyps. Darker blood mixed into the stool may come from higher in the digestive tract. Causes range from hemorrhoids and inflammatory bowel disease to colon cancer and intestinal infections. Any new rectal bleeding, especially in someone over 45, or bleeding accompanied by pain, weight loss, or changes in bowel habits warrants prompt medical evaluation.

ICD-10: K92

Blood in the urine, medically called hematuria, can make urine appear pink, red, or cola-colored. Gross hematuria is visible to the naked eye; microscopic hematuria is detectable only on a urine test. Common causes include urinary tract infections, kidney stones, bladder or kidney infections, vigorous exercise, and injury. More serious causes include kidney disease, bladder cancer, or kidney cancer. Blood in the urine should never be assumed to be benign and requires a medical evaluation every time it occurs. Even a single episode of visible blood in the urine in an adult is a reason to contact a healthcare provider promptly.

ICD-10: R31

Blood pressure monitoring is the ongoing measurement of the force of blood pushing against artery walls, expressed as two numbers: systolic (top number, pressure during heartbeat) over diastolic (bottom number, pressure between beats). In hospitals, an automatic cuff inflates on your arm at regular intervals. Normal adult blood pressure is generally around 120/80 mmHg. Very high readings (hypertensive crisis) or very low readings (hypotension) are emergencies requiring immediate treatment. In the ICU or post-surgery, blood pressure may be monitored continuously through an arterial line inserted into a wrist artery.

A blood transfusion is a medical procedure in which donated blood or blood components such as red blood cells, platelets, or plasma are given through an intravenous (IV) line into a patient's vein. It is used to replace blood lost during surgery, injury, or childbirth; to treat anemia or bleeding disorders; or to provide platelets to patients with certain cancers or during chemotherapy. Before transfusion, the blood type is matched carefully to prevent reactions. The procedure usually takes one to four hours per unit. A nurse monitors the patient closely during the transfusion for signs of a reaction such as fever, chills, or rash. Most transfusions are safe and life-saving.

Blood typing identifies whether your blood group is A, B, AB, or O and whether you are Rh-positive or Rh-negative. A crossmatch test goes further by mixing a small amount of your blood with donor blood to confirm they are compatible before a transfusion. The lab checks for any reaction that would signal incompatibility. Blood is drawn from a vein in your arm. This testing is done before surgeries where blood loss is expected, before planned transfusions, and during pregnancy. Receiving incompatible blood can cause a life-threatening transfusion reaction, so this step is mandatory in hospitals before any blood product is given.

The blood urea nitrogen (BUN) test measures the amount of urea nitrogen in your blood. Urea is a waste product formed when your liver breaks down protein from food. Healthy kidneys filter urea out of the blood into urine. A high BUN level can signal that your kidneys are not filtering properly, or that you are dehydrated or eating a very high-protein diet. Blood is drawn from a vein in your arm. BUN is almost always interpreted together with creatinine; the BUN-to-creatinine ratio helps doctors distinguish between kidney problems and dehydration. Normal adult BUN is roughly 7–20 mg/dL.

Blurred vision is when your eyesight appears out of focus, hazy, or unclear, and can affect one or both eyes. Common non-urgent causes include nearsightedness, farsightedness, dry eyes, eye fatigue, and low blood sugar. More serious causes include diabetic retinopathy, high blood pressure damaging retinal vessels, cataracts, glaucoma, and stroke. Sudden blurred vision — especially in only one eye or combined with headache, eye pain, nausea, or other neurological symptoms — requires emergency evaluation. Call 911 or go to an emergency room right away. Gradual blurring should be assessed by an eye doctor. Poorly controlled diabetes and high blood pressure are leading preventable causes.

ICD-10: H53

Body temperature is measured in Fahrenheit (F) or Celsius (C) in US hospitals. Normal adult temperature is approximately 98.6°F (37°C), though it can vary slightly by individual and time of day. A fever of 100.4°F (38°C) or higher often signals infection. Temperatures at or above 104°F (40°C) or below 95°F (35°C, hypothermia) are emergency situations. Hospitals may measure temperature orally (mouth), rectally, in the ear, on the forehead, or via a special catheter or probe for ICU patients. Persistent or very high fever may lead to diagnostic tests and immediate treatment.

Bone marrow is the soft, spongy tissue found inside certain bones, such as the hips, thighs, and chest. It is the body's blood cell factory. Red bone marrow produces red blood cells, which carry oxygen; white blood cells, which fight infections; and platelets, which help blood clot. In adults, red bone marrow is found mainly in flat bones like the pelvis, sternum, and vertebrae. A bone marrow biopsy is a procedure where a small sample is taken — usually from the hip bone — to diagnose blood disorders, anemia, or cancers like leukemia and lymphoma. Bone marrow transplants can treat certain blood cancers and immune disorders.

A bone marrow biopsy removes a small core of bone marrow — the spongy tissue inside large bones that produces blood cells — for laboratory analysis. A doctor typically takes the sample from the back of your hip bone (iliac crest) using a special needle after numbing the area with local anesthetic. You may feel pressure and a sharp ache as the needle enters the bone. A companion procedure called a bone marrow aspiration withdraws liquid marrow. Together they help diagnose blood cancers (leukemia, lymphoma, myeloma), bone marrow failure, unexplained anemia, and certain infections. The procedure takes about 30 minutes and is performed in an outpatient or hospital setting.

A bone marrow transplant, also called a stem cell transplant, replaces diseased or damaged bone marrow with healthy blood-forming stem cells. It is used to treat blood cancers such as leukemia and lymphoma, as well as aplastic anemia and certain genetic disorders. Stem cells may come from a matched donor (allogeneic) or from the patient's own previously collected cells (autologous). Before transplant, high-dose chemotherapy or radiation destroys the existing bone marrow. The new stem cells are infused through an IV and migrate to the bone marrow to begin producing healthy blood cells. Recovery takes months and requires careful infection precautions due to a severely weakened immune system. Hospitalization lasts several weeks.

A bone scan is a nuclear medicine imaging test that detects areas of abnormal bone activity, such as cancer spread, fractures, infections, or arthritis. A small amount of radioactive tracer is injected into a vein in your arm. You will wait two to four hours for the tracer to travel through your bloodstream and be absorbed by your bones. Then you lie still on a table while a special camera moves slowly over your body to detect the radiation emitted by the tracer. The scan itself takes 30 to 60 minutes. Areas of increased tracer uptake appear as hot spots. You should drink plenty of water after the injection to help flush the tracer out of your body through your urine.

Borderline personality disorder (BPD) is a mental health condition that affects how a person regulates emotions, perceives themselves and others, and maintains relationships. People with BPD may experience intense emotional swings, a strong fear of abandonment, impulsive behavior, unstable self-image, and difficulties in relationships. These experiences can be painful and overwhelming. BPD often develops in the context of trauma and is frequently misunderstood. It is a real and treatable diagnosis. Dialectical Behavior Therapy (DBT) is the leading evidence-based treatment and teaches skills for managing emotions, tolerating distress, and improving relationships. With appropriate care, many people with BPD experience significant improvement in their quality of life.

ICD-10: F60

The brainstem is the stalk-like structure at the base of your brain that connects the brain to the spinal cord. It controls many automatic functions your body needs to survive, including breathing, heart rate, blood pressure, and swallowing. The brainstem also manages sleep cycles, your ability to stay awake, and many reflexes. Most of the signals traveling between your body and brain pass through the brainstem. It consists of three parts: the midbrain, pons, and medulla oblongata. Injury or disease in the brainstem can be life-threatening because it controls so many vital functions. Brain death is defined by the permanent loss of brainstem activity.

A brand-name drug is a medication sold under a proprietary trade name by the pharmaceutical company that developed it and holds the patent. Brand-name drugs are typically placed in higher formulary tiers with higher cost-sharing. Once the patent expires, other manufacturers can produce FDA-approved generic versions. Some conditions may require brand-name drugs when generics are not therapeutically interchangeable; insurers may require prior authorization or step therapy before covering brand-name options.

Breast cancer is a malignant tumor that begins in the breast tissue, most commonly in the milk ducts or lobules. It is the most common cancer in American women. Early detection through mammograms significantly improves survival rates. Treatment depends on the stage and type, but may include surgery, radiation, chemotherapy, hormone therapy, or targeted therapy. Many early-stage breast cancers have excellent outcomes. Regular self-exams and mammograms are key to catching it early. Men can also develop breast cancer, though it is rare.

ICD-10: C50

Breastfeeding is feeding your baby with milk produced by your own body. The American Academy of Pediatrics (AAP) recommends exclusive breastfeeding for the first 6 months, then continuing alongside solid foods until at least 12 months. Breast milk provides antibodies, nutrients, and hormones tailored to your baby's needs. Early milk, called colostrum, is especially rich in immune factors. Breastfeeding also benefits the mother by reducing risks of breast cancer, ovarian cancer, and postpartum depression. Many challenges like latch problems or low supply can be addressed with help from a lactation consultant.

ICD-10: Z39

The bronchi are two large air passages that branch off the bottom of the trachea — the windpipe — and carry air into the right and left lungs. Think of them as the main hallways that lead air into your lungs. Inside each lung the bronchi keep dividing into smaller and smaller tubes, eventually becoming tiny passages called bronchioles that end in the air sacs where oxygen enters your blood. When the bronchi become inflamed or narrowed — as happens in asthma or bronchitis — breathing feels tight or wheezy. Doctors may order a chest X-ray or CT scan to look at the bronchi and may perform a procedure called a bronchoscopy to see inside them.

Bronchodilators are medications that relax and open the airways in the lungs, making it easier to breathe. They are used to treat asthma, chronic obstructive pulmonary disease (COPD), and other respiratory conditions. They come in two main types: short-acting (rescue inhalers used during an attack, such as albuterol) and long-acting (used daily for ongoing control). Proper inhaler technique is essential for the medication to reach your lungs. If you are using your rescue inhaler more than twice a week, your condition may not be well controlled — talk to your doctor. Rinse your mouth after using inhaled corticosteroid-combination inhalers to prevent mouth infections.

A bronchoscopy allows a doctor to look directly inside the airways of your lungs using a thin, flexible tube with a light and camera called a bronchoscope. It is passed through your nose or mouth, down your throat, and into the airways. You will receive a sedative and a local anesthetic spray to numb your throat. You may feel pressure or the urge to cough during the procedure. It usually takes 30 to 60 minutes. Bronchoscopy is used to diagnose lung infections, investigate persistent cough or coughing up blood, take tissue biopsies, or remove foreign objects. You must fast for several hours beforehand. Afterward, your throat may feel sore and you will need a ride home due to sedation.

Bruising occurs when small blood vessels under the skin break after an impact, causing discoloration ranging from red and purple to green and yellow as the bruise heals. Occasional bruising from minor injuries is normal. However, bruising easily without obvious injury, bruises that are unusually large, or bruises that appear on the trunk or face without trauma may signal a bleeding disorder, vitamin deficiency, or side effects from blood thinners or aspirin. Certain medical conditions such as leukemia or liver disease also increase bruising. Seek evaluation if bruising is frequent, unexplained, or accompanied by other bleeding symptoms.

ICD-10: R23

A bundled payment is a single combined payment made to cover all healthcare services related to a specific treatment, episode of care, or condition — such as a knee replacement — rather than paying each provider separately. The bundle typically includes surgeon fees, hospital costs, anesthesia, physical therapy, and follow-up visits. Providers split the bundled amount among themselves. For patients, bundled payments can mean fewer separate bills and more coordinated care. If your care falls under a bundled payment arrangement, you pay your usual cost-sharing, but providers handle the financial coordination behind the scenes.

A burning sensation is a feeling of heat or fire in a specific area of the body without an external heat source. It is commonly felt in the chest (heartburn), throat, stomach, skin, feet, hands, or along a nerve path. Causes include acid reflux, urinary tract infections, peripheral neuropathy, nerve damage, skin conditions such as dermatitis or shingles, or reactions to medications. The severity can range from mild and annoying to intense and disabling. Tell your provider where the burning is, when it started, how long it lasts, and whether anything makes it better or worse, to help identify the underlying cause.

Bursitis is inflammation of a bursa—a small, fluid-filled sac that cushions bones, tendons, and muscles near joints. When a bursa becomes inflamed due to overuse, injury, or repetitive pressure, it causes localized pain, swelling, and limited movement. The most commonly affected sites are the shoulder, elbow, hip, and knee. People who perform repetitive motions at work or in sport are at higher risk. Most cases resolve with rest, ice, and anti-inflammatory medications, but persistent bursitis may need corticosteroid injections, physical therapy, or rarely, surgical drainage of the inflamed bursa.

ICD-10: M70

Under the federal HIPAA Privacy Rule, a business associate is any company or individual that performs services for a HIPAA-covered entity—such as a hospital, clinic, or health insurer—and in doing so, creates, receives, maintains, or transmits your protected health information (PHI). Common business associates include billing companies, electronic health record vendors, cloud storage providers, and legal firms. Business associates are legally required to sign a Business Associate Agreement (BAA) and follow the same HIPAA privacy and security requirements as the covered entity itself. If a business associate breaches your PHI, you can file a complaint with the HHS Office for Civil Rights. Understanding who qualifies as a business associate helps you know which organizations are legally obligated to protect your health data.

C-reactive protein (CRP) is a protein your liver releases into the blood in response to inflammation or infection. A CRP blood test measures how much of this protein is circulating. A standard CRP test detects significant inflammation from infections, autoimmune flares, or tissue injury. A high-sensitivity CRP (hs-CRP) test detects much smaller amounts and is used to assess cardiovascular risk. Blood is drawn from a vein in your arm and no special preparation is needed. CRP levels can rise and fall rapidly — within hours — making this test useful for tracking how well treatment is controlling inflammation. See also: CRP test entry for hs-CRP specifics.

Capitation is a payment model in which a health plan pays a fixed monthly amount per enrolled patient to a provider or medical group — regardless of how many services that patient actually uses. Instead of billing per visit, the provider receives a set per-member, per-month (PMPM) fee to cover all contracted services. This model is common in HMO plans. For patients, capitation means your PCP is paid the same whether you visit once or ten times in a month. Providers have a financial incentive to focus on preventive care to keep patients healthy rather than ordering unnecessary tests.

A capsule is a dosage form in which medication is enclosed within a gelatin or vegetarian shell that dissolves after you swallow it, releasing the drug inside. Hard-shell capsules contain powder or small beads, while soft-gel capsules contain liquid medication. Some capsules can be opened and the contents mixed with a small amount of food or liquid if swallowing is difficult; however, others, especially extended-release or enteric-coated capsules, must not be opened because this can alter how the drug is absorbed. Always check with your pharmacist before opening any capsule to confirm whether it is safe to do so.

Cardiac ablation is a procedure used to correct heart rhythm abnormalities (arrhythmias) by destroying small areas of heart tissue that cause irregular electrical signals. A cardiologist threads thin, flexible tubes called catheters through a blood vessel into the heart. The tip of the catheter delivers energy — radiofrequency heat, laser, or extreme cold — to scar the problematic tissue and interrupt abnormal electrical pathways. The procedure is performed in a cardiac catheterization lab under sedation or anesthesia. It can effectively treat atrial fibrillation, atrial flutter, and other arrhythmias, often reducing or eliminating the need for long-term antiarrhythmic medications.

Cardiac catheterization is an invasive procedure in which a thin, flexible tube called a catheter is inserted into a blood vessel in your groin, wrist, or arm and guided to your heart. A contrast dye is injected through the catheter so doctors can use X-ray imaging to see your coronary arteries and heart chambers clearly. You will be awake but sedated. A local anesthetic numbs the insertion site. The procedure takes one to three hours. It is used to diagnose blockages, measure pressures inside the heart, and evaluate heart valve function. If a blockage is found, a stent or balloon angioplasty may be performed during the same session. Recovery involves lying still for several hours afterward.

Cardiac monitoring is the continuous or prolonged observation of your heart's electrical activity and rhythm. In a hospital or clinic, this is done by connecting electrodes to your chest that transmit your heart's signals to a bedside monitor watched by nurses or technicians. Outpatient monitoring uses wearable devices such as a Holter monitor, event recorder, or implantable loop recorder that record your heart rhythm over days, weeks, or months while you go about daily life. Some devices transmit data wirelessly to your doctor in real time. Monitoring is ordered when a doctor suspects irregular heart rhythms that occur too infrequently to capture during a standard EKG. No radiation is involved. You will be instructed to keep a symptom diary.

Cardiac rehabilitation is a supervised medical program designed to help people recover after a heart attack, heart surgery, or diagnosis of heart failure. The program typically includes monitored exercise sessions, education about heart-healthy eating, guidance on managing risk factors such as high blood pressure and cholesterol, stress management, and counseling. Sessions are held at a hospital or outpatient facility three times per week for several weeks. Heart rate, blood pressure, and symptoms are closely monitored during exercise. The goal is to strengthen the heart, reduce the risk of future cardiac events, and improve quality of life.

A cardiac stress test evaluates how well your heart works during physical activity. Electrodes are placed on your chest to record your heart rhythm, and your blood pressure is monitored throughout. You will walk on a treadmill or pedal a stationary bike at increasing speeds and inclines until you reach a target heart rate. If you cannot exercise, a medication can be given to artificially increase your heart rate. The test usually lasts 30 to 60 minutes total. You should avoid caffeine and certain medications beforehand. Wear comfortable walking shoes. A nuclear or echocardiographic stress test may add imaging before and after exercise to capture heart function images.

Cardiomyopathy refers to diseases of the heart muscle that make it harder for the heart to pump blood to the rest of the body. The heart muscle may become enlarged, thickened, or stiff. As cardiomyopathy worsens, the heart becomes weaker and may lead to heart failure, arrhythmias, or sudden cardiac arrest. Common types include dilated (enlarged heart), hypertrophic (thickened heart muscle), and restrictive (stiff heart). Causes include genetics, prior heart attack, viral infections, and excessive alcohol use. Symptoms include shortness of breath, fatigue, leg swelling, and palpitations. Treatment includes medications, lifestyle changes, devices, or heart transplant in severe cases.

ICD-10: I42

The Coronavirus Aid, Relief, and Economic Security (CARES) Act is a federal law signed in March 2020 in response to the COVID-19 pandemic. For patients, it had several important effects: it required most private health plans and Medicare to cover COVID-19 testing and vaccines at no cost; it expanded telehealth access by allowing Medicare to pay for virtual visits; it broadened what expenses qualify for health savings accounts (HSAs) and flexible spending accounts (FSAs), including over-the-counter drugs without a prescription; and it provided financial relief to hospitals and healthcare providers. Many CARES Act provisions were temporary, and some have since expired or changed. If you received pandemic-related healthcare, understanding the CARES Act may help you clarify billing questions.

The carotid arteries are the main blood vessels that carry oxygen-rich blood from the heart to the brain, neck, and face. There is one on each side of the neck — you can feel the pulse in the carotid artery on either side of your windpipe. Each carotid artery divides into two branches: the internal carotid, which supplies the brain, and the external carotid, which supplies the face and neck. Plaque buildup in the carotid artery wall (carotid artery disease) can narrow the artery and block blood flow to the brain, causing a stroke or transient ischemic attack (TIA, also called a mini-stroke). Doctors listen to the carotid artery with a stethoscope for abnormal sounds called bruits.

Carpal tunnel syndrome occurs when the median nerve, which runs through a narrow passage in the wrist called the carpal tunnel, becomes compressed. This causes numbness, tingling, and pain in the thumb, index, middle, and part of the ring finger, and can cause weakness in grip. Symptoms often worsen at night or with repetitive hand use. Risk factors include repetitive wrist motions, pregnancy, diabetes, and thyroid disease. Treatment ranges from wrist splints and corticosteroid injections to carpal tunnel release surgery in persistent or severe cases.

ICD-10: G56

Cartilage is a firm but flexible tissue found throughout the body that cushions joints and provides structure. The most important type for joints is articular cartilage, which covers the ends of bones where they meet, allowing smooth, pain-free movement. Cartilage does not contain blood vessels, making it slow to heal once damaged. When cartilage wears down over time — as happens in osteoarthritis — the bones begin to rub against each other, causing pain, stiffness, and swelling. Cartilage also gives shape to your nose and ears, and is found in your windpipe and rib cage. Injuries and aging are the most common causes of cartilage damage.

Casting involves applying a rigid protective shell — usually made of plaster or fiberglass — around a broken bone or injured joint to hold it in proper alignment while it heals. A clinician wraps the area with padding and then applies the casting material, which hardens within minutes. Casts are worn for several weeks to months depending on the injury. You must keep the cast dry and avoid inserting objects inside it. Follow-up X-rays confirm the bone is healing correctly. When healing is complete, the cast is cut off with a specialized saw and removed safely.

Cataract surgery is a procedure to remove a cloudy lens from the eye and replace it with a clear artificial lens called an intraocular lens (IOL). It is one of the most common and safest surgeries performed in the United States. The procedure is done under local anesthesia with light sedation and takes about 15 to 30 minutes. Only one eye is treated at a time, with the second eye scheduled weeks later if needed. Most patients notice improved vision within days. You will need to use prescription eye drops for several weeks after surgery. Driving and lifting restrictions apply for a few days. Avoid rubbing or pressing on the eye during recovery.

A cataract is a clouding of the eye's natural lens, which lies behind the iris and pupil. Cataracts are the leading cause of vision loss in people over 40 and the most common cause of blindness worldwide. Symptoms include blurry or hazy vision, difficulty seeing at night, sensitivity to light, and faded colors. Aging is the most common cause, but cataracts can also result from diabetes, steroid use, or eye injury. Cataract surgery, which replaces the cloudy lens with an artificial one, is one of the safest and most effective surgeries performed.

ICD-10: H26

A catastrophic health plan is a type of ACA marketplace plan designed for people who want protection against worst-case medical costs but are willing to pay most routine expenses out of pocket. Catastrophic plans have very low monthly premiums but very high deductibles—equal to the ACA's annual out-of-pocket maximum (over $9,000 for single coverage in most years). After you meet the deductible, the plan covers 100% of covered costs. Catastrophic plans are only available to people under age 30 or those who qualify for a hardship or affordability exemption. They do cover three primary care visits per year and preventive services at no cost. These plans are generally not eligible for income-based premium tax credits.

A catastrophic health plan is a type of ACA-compliant health insurance with very low monthly premiums and a very high annual deductible — equal to the ACA's out-of-pocket maximum limit (over $9,000 for an individual in 2024). Catastrophic plans cover three primary care visits per year at no cost and all ACA-required preventive services before the deductible. They are available only to people under age 30 or to those who qualify for a hardship or affordability exemption. Because premiums are very low, these plans are designed to protect against worst-case medical scenarios while keeping everyday costs out-of-pocket. You cannot use premium tax credits with a catastrophic plan.

The Centers for Disease Control and Prevention (CDC) is the leading federal public health agency in the United States, operating under HHS. The CDC conducts research on disease prevention, monitors health trends, responds to outbreaks and public health emergencies, and provides health information to the public. It develops vaccination schedules and clinical guidelines used by healthcare providers nationwide. The CDC's website (cdc.gov) is an authoritative source of health information including vaccine recommendations, travel health advisories, and disease statistics.

The cecum is a pouch-like structure in the lower right part of the abdomen that marks the beginning of the large intestine. Material from the small intestine enters the cecum through the ileocecal valve. The cecum is a short, rounded pocket from which the ascending colon — the first part of the large intestine — rises upward. The appendix is a small worm-shaped projection that hangs off the bottom of the cecum. In many languages the word for appendicitis translates literally as an illness of the cecum because the appendix grows from it. Cecal volvulus — a rare condition where the cecum twists on itself — can cause a bowel obstruction requiring emergency surgery.

The celiac artery, also called the celiac trunk, is a short but important blood vessel that branches off the aorta just below the diaphragm in the upper abdomen. It immediately divides into three branches that supply blood to the three major upper abdominal organs: the hepatic artery supplies the liver, the splenic artery supplies the spleen, and the left gastric artery supplies the stomach. The celiac artery can sometimes be compressed by a ligament in the diaphragm — a rare condition called celiac artery compression syndrome or median arcuate ligament syndrome — causing abdominal pain after eating. Surgeons must carefully identify and protect the celiac artery during many abdominal operations.

Celiac disease is a chronic autoimmune disorder in which eating gluten, a protein found in wheat, barley, and rye, triggers an immune response that damages the small intestine's lining. Over time this damage impairs nutrient absorption, leading to malnutrition. Symptoms include diarrhea, bloating, gas, abdominal pain, fatigue, weight loss, and anemia. Some people experience skin rash, bone or joint pain, or neurological symptoms. Celiac disease is diagnosed by blood tests and confirmed with a small intestine biopsy. The only effective treatment is a strict lifelong gluten-free diet. Untreated celiac disease increases the risk of serious complications including bone loss, infertility, and certain cancers.

ICD-10: K90

Cellulitis is a common bacterial skin infection that affects the deeper layers of the skin and the tissue just beneath it. It most often occurs on the lower legs but can appear anywhere on the body. It develops when bacteria, usually streptococcus or staphylococcus, enter through a cut, wound, or area of dry cracked skin. Symptoms include redness, swelling, warmth, and pain in the affected area, sometimes accompanied by fever. Mild cases are treated with oral antibiotics. Severe or spreading infections may require intravenous antibiotics and hospitalization. People with diabetes, a weakened immune system, or chronic skin conditions are at higher risk.

ICD-10: L03

A central venous catheter (CVC), also called a central line, is a longer IV catheter inserted into a large vein near the neck, chest, or groin that reaches close to the heart. It is used when a patient needs multiple medications simultaneously, long-term IV access, certain monitoring, or when peripheral veins cannot be used. Placing a CVC is a sterile procedure done by a physician. It allows more reliable and stable access than a regular IV. Central lines carry risks including infection and blood clots, so hospital staff follow strict protocols to prevent complications. Your care team will remove the central line as soon as you no longer need it.

The cerebellum is a compact, rounded part of the brain located at the lower back of your head, just above the brainstem. Though it is much smaller than the cerebrum, it plays a critical role in coordinating movement, balance, and fine motor control. It helps you walk in a straight line, write clearly, and reach for objects accurately. The cerebellum receives signals from your muscles, joints, and inner ear and constantly fine-tunes your movements. Damage or disease affecting the cerebellum can cause clumsiness, unsteady walking (called ataxia), slurred speech, and difficulty with precise hand movements. Strokes, tumors, and alcohol can all affect it.

Cerebral palsy (CP) is a group of permanent movement and posture disorders caused by damage to the developing brain, usually before or around birth. It affects muscle control, coordination, and balance to varying degrees. Symptoms range from mild clumsiness to severe movement impairment requiring a wheelchair. Many individuals also have intellectual disabilities, communication challenges, or seizures. CP does not get worse over time, but its effects change as the person grows. Treatment is lifelong and focuses on maximizing independence through physical, occupational, and speech therapy, along with medications and sometimes surgery to manage muscle spasticity.

ICD-10: G80

The cerebrum is the largest part of your brain, filling most of the skull. It controls your thoughts, memory, speech, emotions, and voluntary movements like walking and picking up objects. The cerebrum is divided into two halves called hemispheres, and each half is divided into four lobes: frontal, temporal, parietal, and occipital. The right hemisphere generally controls the left side of your body, and the left hemisphere controls the right side. Doctors may refer to the cerebrum when discussing strokes, tumors, or injuries that affect thinking, movement, or speech. Damage to different areas produces different symptoms depending on location.

Cervical cancer is a malignant tumor of the cervix, the lower part of the uterus that connects to the vagina. It is most often caused by human papillomavirus (HPV). Regular Pap smears and HPV tests can detect precancerous changes early, making cervical cancer highly preventable. The HPV vaccine also greatly reduces risk. When detected early, cervical cancer has excellent survival rates. Symptoms may include unusual vaginal bleeding or pelvic pain. Treatment may involve surgery, radiation, and chemotherapy depending on the stage.

ICD-10: C53

The cervical vertebrae are the seven bones that make up the neck portion of your spine, labeled C1 through C7. They sit at the very top of your spinal column, starting just below the skull and ending at the top of the chest. These small but critical bones support the weight of your head, protect your spinal cord and nerves, and allow your neck to move in many directions. C1 and C2, sometimes called the atlas and axis, are specially shaped to allow head rotation. Cervical spine injuries, such as fractures or herniated discs, can affect the nerves running to your arms, hands, and shoulders.

The cervix is the lower, narrow portion of the uterus that connects to the vagina. It forms a natural opening called the cervical os, which allows menstrual blood to pass from the uterus and allows sperm to enter during intercourse. During childbirth, the cervix softens and dilates (opens) to allow the baby to be born. A Pap smear, also called a Pap test, is a routine screening that collects cells from the cervix to check for abnormal changes that could indicate cervical cancer or precancerous conditions. HPV infection is the primary cause of cervical cancer. Regular screenings can detect problems early when they are most treatable.

A cesarean section, also called a C-section, is a surgical procedure in which a baby is delivered through incisions made in the mother's abdomen and uterus. It may be planned in advance due to certain health conditions or complications, or it may be performed as an emergency during labor. Most C-sections use regional anesthesia such as an epidural or spinal block so the mother stays awake. The surgery takes about 45 minutes and recovery in the hospital typically lasts two to four days. Full recovery at home may take six to eight weeks. Activity restrictions apply, especially lifting, to protect the incision.

The Consumer Financial Protection Bureau (CFPB) is a federal agency established in 2011 to protect consumers from unfair, deceptive, or abusive financial practices. For patients with medical debt, the CFPB is an important resource: it enforces the Fair Debt Collection Practices Act (FDCPA), which limits how debt collectors can contact you and prohibits harassment; it accepts consumer complaints against debt collectors, credit bureaus, and medical billing companies; and it has taken action to limit how medical debt can appear on credit reports. If you believe a debt collector is harassing you or a credit bureau has wrongly reported a medical debt, you can submit a complaint at consumerfinance.gov. The CFPB also publishes guides on understanding your rights with medical debt.

A change in bowel habits refers to any noticeable and persistent difference from your normal pattern of bowel movements. This can include a change in stool frequency (going more or less often), stool consistency (harder, looser, narrower), color, or the need to strain. It can also mean alternating between diarrhea and constipation. While temporary changes often relate to diet or illness, changes that persist for more than a few weeks should be evaluated, especially in adults over 45. Unexplained changes in bowel habits can be an early warning sign of colorectal cancer, inflammatory bowel disease, or other significant gastrointestinal conditions.

ICD-10: R19

A chargemaster—also called a charge description master (CDM)—is a hospital's internal list of standard prices for every service, procedure, drug, supply, and room charge it provides. These list prices are almost never what patients or insurers actually pay; in practice, insurers negotiate large discounts off chargemaster rates, and government programs like Medicare and Medicaid set their own payment rates independently. Under the Hospital Price Transparency Rule, most U.S. hospitals must post their chargemaster rates and negotiated prices publicly online. While chargemaster prices can feel alarming, the key numbers to focus on are your insurer's allowed amount and your share of cost-sharing. If you are uninsured, ask about financial assistance or the hospital's amounts generally billed policy.

Charity care is free or reduced-cost medical care provided by hospitals to patients who cannot afford to pay. Non-profit hospitals are required by federal law to have written financial assistance policies (FAPs) and must provide charity care as a condition of their tax-exempt status. Eligibility is typically income-based, often using a percentage of the federal poverty level. Patients must apply — charity care is not automatic — and may need to provide income documentation. Applications can often be submitted after receiving care.

Chemotherapy uses powerful drugs to kill or slow the growth of cancer cells throughout the body. It may be given by IV infusion, injection, or oral pill. Sessions often take place in a clinic or infusion center and may last from thirty minutes to several hours. Treatment courses typically span weeks or months, with rest periods in between. Common side effects include nausea, fatigue, hair loss, and increased risk of infection. The goal is to shrink tumors, prevent cancer spread, or eliminate cancer cells that remain after surgery.

Chest pain is any discomfort, pressure, tightness, squeezing, or aching feeling in the chest area. It can range from mild to severe. Causes include heart problems (such as a heart attack or angina), lung issues (like pneumonia or blood clots), acid reflux, muscle strain, or anxiety. Some chest pain spreads to the arm, jaw, or back. Seek emergency care immediately if chest pain is sudden, severe, or comes with shortness of breath, sweating, dizziness, or arm pain, as these may signal a heart attack. Even mild or unusual chest pain should be evaluated by a provider.

ICD-10: R07

Chest tightness is the feeling that your chest is being squeezed, pressed, or constricted. It can range from mild discomfort to severe pressure. In the context of respiratory disease, it commonly signals asthma, COPD, or a chest infection. However, chest tightness can also be a warning sign of heart attack, angina, pulmonary embolism, or severe anxiety. Chest tightness accompanied by shortness of breath, pain radiating to the arm or jaw, sweating, or nausea is a medical emergency — call 911 immediately. Even if you think it is asthma, new or unusual chest tightness should be reported to your doctor.

ICD-10: R06

Chickenpox is a highly contagious viral infection caused by the varicella-zoster virus. It causes an itchy blister-like rash that appears first on the chest, back, and face and then spreads over the body. Other symptoms include fever, tiredness, and loss of appetite. The rash goes through stages of red spots, fluid-filled blisters, and then crusting. Most children recover without serious problems, but adults and people with weakened immune systems can experience severe complications such as pneumonia or encephalitis. The varicella vaccine effectively prevents chickenpox. Antiviral medication may be prescribed for high-risk patients. After infection, the virus stays dormant and can reactivate later in life as shingles.

ICD-10: B01

The chief complaint is the main reason a patient seeks medical care, described in the patient's own words. It is one of the first pieces of information documented when you arrive at the emergency room or a clinic. Examples include 'chest pain,' 'shortness of breath,' or 'fever for three days.' Clearly stating your chief complaint helps staff triage you correctly and begin appropriate workup faster. Be as specific as possible: describe when the problem started, where you feel it, how severe it is, and whether anything makes it better or worse. This information directly shapes the care plan.

Childhood vaccines are shots given to babies and children to protect them from serious infectious diseases by training the immune system to recognize and fight specific germs. In the US, routine childhood vaccines protect against 16 diseases including measles, chickenpox, whooping cough, polio, meningitis, and hepatitis B. Vaccines are rigorously tested for safety and effectiveness before approval. Side effects are usually mild — a sore arm or low fever. Serious reactions are very rare. Following the CDC's recommended schedule is important because it protects children at the age they are most vulnerable to each disease.

ICD-10: Z23

Chills are episodes of shivering and feeling cold, often without an obvious environmental cause. They most often accompany fever as the body tries to raise its temperature to fight infection. Common infectious causes include the flu, urinary tract infections, pneumonia, and malaria. Chills also occur with low blood sugar and certain medications. Rigors are severe uncontrollable shaking chills associated with high fever and can indicate a serious infection such as sepsis. Call 911 or go to the ER if chills come with a very high fever above 103°F (39.4°C), confusion, difficulty breathing, rash, or rapid heartbeat, as these may indicate life-threatening infection requiring emergency treatment.

ICD-10: R68

CHIP (Children's Health Insurance Program) provides low-cost health coverage to children in families that earn too much to qualify for Medicaid but cannot afford private insurance. Coverage includes doctor visits, immunizations, hospital care, dental, and vision. Some states extend CHIP coverage to pregnant women. CHIP is jointly funded by federal and state governments and administered by states; income eligibility thresholds vary by state. Most children pay no premiums, though some states charge modest premiums.

A cholecystectomy is surgical removal of the gallbladder, a small organ beneath the liver that stores bile. It is most often performed to treat gallstones that cause pain, infection, or blockage. The procedure is typically laparoscopic, using three or four tiny incisions, and takes about one hour under general anesthesia. Most patients go home the same day or the next morning. You can expect soreness around the incision sites and possible shoulder discomfort from surgical gas for a day or two. Full recovery takes one to two weeks for laparoscopic surgery. Your body continues to produce and use bile normally without the gallbladder.

Chronic bronchitis is a long-term inflammation of the bronchial tubes characterized by a productive cough lasting at least three months per year for two or more consecutive years. It is a form of COPD and is most commonly caused by cigarette smoking or long-term exposure to irritants such as dust, fumes, or air pollution. Symptoms include persistent cough with mucus, shortness of breath, wheezing, and frequent respiratory infections. There is no cure, but quitting smoking, using inhalers, and pulmonary rehabilitation can manage symptoms effectively and slow disease progression.

ICD-10: J42

Chronic fatigue syndrome (ME/CFS) is a complex, long-term condition characterized by extreme fatigue that is not improved by rest and worsens significantly with physical or mental activity—a hallmark called post-exertional malaise. Other symptoms include unrefreshing sleep, cognitive difficulties (brain fog), dizziness on standing, and widespread pain. The cause is unknown but often follows an infection. It can severely limit a person's ability to work, attend school, or perform daily activities. There is no cure and no approved treatment, but symptom management through pacing, sleep strategies, and careful activity management can help prevent worsening.

ICD-10: G93

Chronic kidney disease (CKD) is a long-term condition in which the kidneys gradually lose their ability to filter waste and excess fluid from the blood. The most common causes are diabetes and high blood pressure. CKD progresses through five stages, with stage 5 (end-stage renal disease) requiring dialysis or a kidney transplant. Early CKD often has no symptoms, so it is detected through blood and urine tests. Symptoms in later stages include fatigue, swelling, and shortness of breath. Controlling blood pressure and blood sugar can slow progression significantly.

ICD-10: N18

Chronic pain is pain that persists or recurs for three months or longer, beyond the expected period of tissue healing. It can affect any part of the body and range from mild to severe. Unlike acute pain, which alerts you to injury, chronic pain often continues even after the original cause has healed and can become a medical condition in its own right. Common examples include chronic back pain, fibromyalgia, arthritis, and persistent headaches. Chronic pain can affect sleep, mood, and daily functioning. Treatment often involves a combination of medications, physical therapy, psychological support, and lifestyle changes aimed at improving quality of life.

Circumcision is the surgical removal of the foreskin — the skin that covers the tip of the penis — typically performed on newborn boys within the first few days of life. It is a personal and often cultural or religious decision. The American Academy of Pediatrics (AAP) states that the health benefits of newborn circumcision outweigh the risks, but the benefits are not great enough to recommend it universally. Potential benefits include reduced risk of urinary tract infections, penile cancer, and some sexually transmitted infections later in life. The procedure is done with local anesthesia. The area heals within 7 to 10 days. Insurance coverage varies by state.

Cirrhosis is a late stage of scarring (fibrosis) of the liver caused by many forms of liver disease and conditions, such as hepatitis and chronic alcoholism. As the liver is repeatedly damaged, healthy liver tissue is replaced with scar tissue that blocks blood flow and prevents the liver from functioning properly. The liver performs vital functions including filtering toxins from the blood, making proteins needed for clotting, and aiding digestion. Symptoms of advanced cirrhosis include jaundice (yellowing of the skin and eyes), abdominal swelling, easy bruising, confusion, and leg swelling. There is no cure, but treatment can slow disease progression and manage complications.

ICD-10: K74

Claims adjudication is the process an insurance company uses to review, evaluate, and decide whether to pay, partially pay, or deny a submitted medical claim. During adjudication, the insurer checks eligibility, confirms coverage, verifies medical necessity, applies the correct payment rules, and calculates what the plan owes versus what you owe. The result is communicated on an Explanation of Benefits (EOB) or remittance advice. Adjudication can result in payment, a request for more information, a denial, or a reduction of the charged amount. If your claim is denied during adjudication, you have the right to appeal.

Claudication is cramping, aching, or fatigue in the leg muscles — most often the calf — that occurs during walking or exercise and is relieved by a few minutes of rest. It is the hallmark symptom of peripheral artery disease (PAD), where narrowed arteries reduce blood flow to the legs. Risk factors include smoking, diabetes, high blood pressure, and high cholesterol. Untreated PAD can progress to critical limb ischemia, where pain occurs at rest and tissue damage may develop. Tell your doctor about leg pain with walking. Rest pain, non-healing wounds, or a suddenly cold pale leg are emergencies requiring immediate care.

ICD-10: I73

A clinical trial is a research study conducted on human participants to evaluate the safety and effectiveness of medical interventions such as new drugs, devices, or procedures. Trials are conducted in phases: Phase I tests safety, Phase II tests efficacy, Phase III compares to existing treatments, and Phase IV monitors long-term effects after approval. Participation is voluntary and requires informed consent. The ACA requires most insurance plans to cover routine costs associated with approved clinical trial participation.

A clinical trial sponsor is the organization that takes legal and financial responsibility for designing, conducting, and overseeing a clinical trial. Sponsors may be pharmaceutical or biotechnology companies, medical device manufacturers, federal agencies such as the National Cancer Institute, academic medical centers, or private foundations. The sponsor must register the trial on ClinicalTrials.gov, ensure that participants are properly informed and protected, and report adverse events to the FDA and IRB. As a patient, knowing who the sponsor is matters because the sponsor may cover certain trial-related costs, provide the experimental treatment for free, or have financial interests that affect how trial results are reported. Always ask your doctor about the sponsor's role before enrolling in a trial.

Cluster headaches are extremely painful headaches that occur in groups or cycles, often at the same time each day, usually for weeks or months. The pain is typically severe, one-sided, and felt around or behind one eye. It often comes with a red or watering eye, runny nose, or drooping eyelid on the same side as the pain. Attacks usually last 15 minutes to three hours. Unlike migraines, people often feel restless or agitated rather than wanting to lie still. Though not life-threatening, cluster headaches are considered one of the most painful conditions known. Treatment includes oxygen therapy, triptan injections, and preventive medications prescribed by a provider.

ICD-10: G44

The Centers for Medicare & Medicaid Services (CMS) is the federal agency within HHS responsible for administering Medicare, Medicaid, CHIP, and the ACA Marketplace. CMS sets payment rates, quality standards, and coverage policies for federal health programs. It oversees the HealthCare.gov marketplace and processes over 1 billion claims per year. CMS also regulates clinical laboratories under CLIA, nursing homes, and home health agencies. It publishes data on hospital quality and cost transparency.

COBRA (Consolidated Omnibus Budget Reconciliation Act) allows workers and their families to continue employer-sponsored group health coverage for a limited period after leaving a job or experiencing other qualifying events such as reduced hours, divorce, or death of the covered employee. COBRA coverage is identical to the former employer plan but the individual typically pays the full premium plus an administrative fee, making it significantly more expensive than when employed. Coverage continues for up to 18 months in most cases.

The COBRA election period is the 60-day window after losing employer-sponsored coverage (or receiving the COBRA election notice) during which an eligible employee or dependent can choose to continue their group health coverage under COBRA. The election deadline is strictly enforced; missing it forfeits the right to COBRA. Coverage, once elected, is retroactive to the date of loss of coverage, meaning a person can wait until they have a medical expense before enrolling and still receive retroactive coverage — though they must pay all retroactive premiums.

The cochlea is a snail-shaped, fluid-filled structure in the inner ear that converts sound vibrations into nerve signals your brain can understand. When vibrations from the middle ear's tiny bones enter the cochlea, they create ripples in the fluid inside. Thousands of tiny hair cells lining the cochlea sense these ripples and generate electrical signals that travel through the auditory nerve to the brain. Different parts of the cochlea respond to different sound frequencies, which is how we distinguish high and low pitches. Damage to the cochlear hair cells — from loud noise exposure, aging, or certain medications — causes permanent hearing loss because these cells do not regenerate. Cochlear implants can restore some hearing for those with severe cochlear damage.

Code Blue is an emergency announcement used in US hospitals indicating that a patient is experiencing cardiac or respiratory arrest — meaning the heart has stopped or the patient is not breathing. When Code Blue is called, a rapid response team rushes to the patient's location with a crash cart containing defibrillators, medications, and other life-saving equipment. CPR is performed until the team arrives. Family members in the room are typically asked to step out. If you hear 'Code Blue' announced overhead, it means staff are responding to a life-threatening emergency somewhere in the hospital. This is a critical emergency requiring immediate medical intervention.

Cognitive Behavioral Therapy (CBT) is a structured, goal-oriented form of psychotherapy that teaches you to recognize and change negative thought patterns and behaviors that contribute to mental health conditions. It is one of the most studied and effective treatments for depression, anxiety disorders, PTSD, OCD, and phobias. Sessions typically last forty-five to sixty minutes and occur weekly over eight to twenty weeks, though duration varies. Your therapist helps you identify unhelpful thinking, challenge those thoughts, and practice new coping strategies. CBT skills can be applied independently long after therapy ends.

Coinsurance is the percentage of costs you pay for a covered service after you have met your deductible. For example, if your plan has 20% coinsurance, your insurer pays 80% and you pay 20% of the allowed amount. Coinsurance applies to most in-network services and continues until you reach your out-of-pocket maximum, after which the insurer covers 100% of covered costs for the rest of the plan year.

Cold extremities — persistently cold hands, feet, fingers, or toes — occur when blood flow to the outer parts of the body is reduced. The most common cause is Raynaud's phenomenon, where blood vessels temporarily spasm in response to cold or stress, turning fingers or toes white, then blue, then red. Other causes include peripheral artery disease (PAD), hypothyroidism, anemia, smoking, and diabetes. While often a minor nuisance, cold extremities accompanied by color changes, non-healing sores, or pain may indicate serious vascular disease. Tell your doctor if the symptom is persistent, worsening, or affects daily life, as treatment can improve circulation and comfort.

ICD-10: I73

Collections refers to the process of pursuing payment on an unpaid medical bill after standard billing has failed. A hospital or provider may first attempt in-house collections through billing statements, phone calls, and payment plan offers. If these efforts fail, the account may be sold to or placed with a third-party debt collection agency. Collection agencies are regulated by the Fair Debt Collection Practices Act (FDCPA), which limits their contact methods and times and prohibits harassment. Unpaid medical debt sent to collections may be reported to credit bureaus and damage your credit score, though recent rule changes have begun to limit this. Before a bill goes to collections, ask about financial assistance, payment plans, and your right to dispute the debt.

The colon, also called the large intestine, is the final part of the digestive tract before waste leaves the body. It is about five feet long and wraps around the edges of the abdomen. After the small intestine absorbs nutrients, the remaining material passes into the colon, where water and electrolytes are absorbed back into the body, turning the liquid waste into formed stool. The colon has four parts: the ascending colon on the right side, the transverse colon across the top, the descending colon on the left, and the sigmoid colon at the bottom. Colorectal cancer, diverticulitis, ulcerative colitis, and irritable bowel syndrome are common conditions that affect the colon.

Colon cancer is a malignant tumor of the large intestine (colon). It often starts as small, noncancerous polyps that can turn cancerous over time. Colonoscopy screening can find and remove polyps before they become cancer. Symptoms may include blood in the stool, changes in bowel habits, or unexplained weight loss. Risk factors include age over 50, family history, and certain diets. Treatment usually involves surgery, and may include chemotherapy or radiation. Screening colonoscopies are recommended starting at age 45 for average-risk individuals.

ICD-10: C18

Colonoscopy is a procedure in which a flexible camera is inserted through the rectum to examine the entire large intestine (colon). It is used to screen for and remove polyps before they become colorectal cancer, and to investigate bleeding, diarrhea, and unexplained abdominal pain. Japan's annual fecal occult blood test (便潜血検査, ben senketsukensa) screens for colon cancer and positive results lead to colonoscopy.

A colonoscopy is a procedure in which a doctor uses a long, flexible tube with a tiny camera to examine the inside of your entire large intestine. Before the procedure, you must completely empty your colon using a bowel preparation — typically a laxative solution taken the day before. You will be given sedation so you will be drowsy or asleep and should feel little to no discomfort. The procedure takes 30 to 60 minutes. The doctor looks for polyps, cancer, inflammation, or other abnormalities. Polyps can often be removed during the same procedure. You will need someone to drive you home afterward. A colonoscopy is typically recommended starting at age 45 for average-risk adults.

A colostomy is a surgical procedure that creates an opening in the abdominal wall (called a stoma) through which a portion of the colon is brought out. Waste passes through the stoma into a pouching system worn outside the body. It is performed when a section of the colon must be removed or bypassed due to colorectal cancer, Crohn's disease, diverticulitis, injury, or obstruction. A colostomy may be temporary, allowing the bowel to rest and heal, or permanent. Surgery is done under general anesthesia. Recovery involves learning stoma care, including how to change the pouch, prevent skin irritation, and manage diet. A wound ostomy continence nurse (WOCN) helps patients adapt to life with a stoma.

Colostrum is the first milk produced by the breasts, starting in late pregnancy and available for the first several days after birth before mature milk comes in. It is thick, yellowish, and produced in very small amounts — just a few teaspoons per day — but it is extremely rich in antibodies, white blood cells, proteins, and growth factors that protect your newborn from infection and help their gut mature. Often called "liquid gold," colostrum is the perfect first food for your baby and provides passive immunity against diseases. Frequent nursing in the first days stimulates more milk production and delivers maximum colostrum to your baby.

A Community Health Needs Assessment (CHNA) is a study that nonprofit hospitals are federally required to complete every three years under IRS Section 501(r). The CHNA identifies the most significant health needs of the people in the hospital's service area, drawing on local public health data, input from community representatives, and feedback from underserved populations. After completing the assessment, the hospital must create and publicize an implementation strategy—a written plan explaining how it will address those needs. CHNAs are public documents, often posted on hospital websites or with the IRS on Form 990 Schedule H. Patients and community members can use them to understand a hospital's community benefit commitments and to advocate for improved services.

A complete blood count (CBC) is one of the most common blood tests ordered by doctors. It measures the number and types of cells in your blood, including red blood cells (which carry oxygen), white blood cells (which fight infection), and platelets (which help blood clot). A laboratory technician draws a small sample of blood from a vein in your arm. Results help doctors diagnose anemia, infections, bleeding disorders, and certain cancers. Your doctor reviews the counts alongside normal reference ranges to decide if further testing or treatment is needed.

A compounding pharmacy prepares customized medications to meet the specific needs of individual patients when commercially available drugs do not fit their requirements. Examples include adjusting drug strength, changing the dosage form (liquid instead of tablet), removing an allergen, or combining medications. Compounding pharmacies are regulated by state pharmacy boards and, in some cases, the FDA. Insurance typically does not cover compounded medications unless prior authorization is obtained. Quality and sterility standards vary among compounding pharmacies.

A comprehensive metabolic panel (CMP) includes all the tests in the basic metabolic panel plus six additional liver-function markers: total protein, albumin, bilirubin, alkaline phosphatase (ALP), aspartate aminotransferase (AST), and alanine aminotransferase (ALT). Together the fourteen measurements give your doctor a broad snapshot of your kidney function, liver health, electrolyte balance, and blood sugar level. Blood is drawn from a vein in your arm. Fasting for eight to twelve hours before the draw is often recommended. Doctors order a CMP for routine physicals, pre-surgical screening, and monitoring of ongoing conditions.

Concurrent review is a type of utilization review conducted by your insurer while you are actively receiving care, most often during a hospital stay. The insurer monitors the ongoing care to determine whether continued hospitalization or treatment is medically necessary and appropriate. Typically, the insurer reviews the case every one to two days and may authorize a set number of additional days. If the insurer decides continued care is no longer necessary, it may issue a non-coverage notice. Patients and providers can appeal this decision before discharge. Concurrent review helps control costs but can create tension between insurer criteria and the provider's clinical judgment.

A concussion is a mild traumatic brain injury caused by a bump, blow, or jolt to the head that temporarily disrupts brain function. Symptoms include headache, dizziness, confusion, memory problems, nausea, sensitivity to light and noise, and feeling foggy or slowed down. Most symptoms resolve within days to weeks with rest, but some individuals develop post-concussion syndrome with lingering symptoms. Repeated concussions can have serious long-term effects on brain health. Return to activity should be graduated and guided by a healthcare provider to avoid second-impact syndrome before full recovery.

ICD-10: S06

Confusion is a state of mental cloudiness where thinking, understanding, or communicating clearly becomes difficult. You may feel disoriented — unsure of where you are, what time it is, or what is happening around you. Causes include infection (especially urinary tract infection in older adults), low blood sugar, dehydration, medication side effects, alcohol, stroke, and head injury. Sudden or severe confusion is a medical emergency — especially if paired with fever, limb weakness, vision changes, or slurred speech. Call 911 in those situations. Mild confusion that clears with rest or fluids is less urgent but should still be reported to a healthcare provider.

ICD-10: R41

Constipation means having fewer than three bowel movements per week, or having stools that are hard, dry, lumpy, and difficult or painful to pass. Common causes include a low-fiber diet, inadequate fluid intake, lack of physical activity, certain medications such as opioids and iron supplements, and conditions such as hypothyroidism or irritable bowel syndrome. Most constipation responds to increased fiber, fluids, and exercise. See your doctor if constipation is new, severe, or persistent, if you notice blood in the stool, unexpected weight loss, or if over-the-counter remedies are not helping after one to two weeks.

ICD-10: K59

Continuous eligibility is a policy under Medicaid and the Children's Health Insurance Program (CHIP) that allows eligible children—and in some states, adults—to remain enrolled in their program for a full 12 months without losing coverage due to changes in family income or circumstances during that period. Without this policy, families that experience income changes mid-year could lose coverage unexpectedly, causing gaps in care. The Consolidated Appropriations Act of 2023 made 12-month continuous eligibility for children under Medicaid and CHIP permanent nationwide. During the COVID-19 pandemic, a related policy called continuous enrollment prevented states from disenrolling anyone from Medicaid. Continuous eligibility helps ensure children have stable access to preventive care, immunizations, and chronic-disease management.

A contraindication is a medical reason why a specific drug should not be used in a particular patient because the risk of harm outweighs the benefit. For example, a blood thinner may be contraindicated in a patient with active internal bleeding. Absolute contraindications mean the drug must never be given under those circumstances, while relative contraindications mean it should generally be avoided but may be used cautiously in select cases. Your doctor and pharmacist review your medical history and current medications to identify contraindications before prescribing or dispensing a new drug. Always share your full health history with your care team.

A controlled substance is a drug regulated by the US federal government under the Controlled Substances Act because it has potential for abuse, addiction, or dependence. Examples include opioid pain relievers, stimulants like Adderall, sedatives, and certain anxiety medications. When your doctor prescribes a controlled substance, they must follow strict rules, and your pharmacy tracks dispensing carefully. You may receive only a limited supply at a time, and refills may require a new prescription each time. The pharmacy will likely ask for a photo ID when you pick it up. Your medication's DEA schedule tells you how tightly it is controlled.

Coordination of benefits (COB) is a process used when a patient is covered by more than one health insurance plan. It determines which plan pays first (the primary plan) and which pays second (the secondary plan) to avoid overpayment. The combined payments from both plans typically cannot exceed the total allowed charges. For example, if you are covered by your own employer plan and your spouse's plan, COB rules decide the order of payment. You must notify both insurers about dual coverage. COB can reduce or eliminate your out-of-pocket costs when handled correctly.

Coordination problems (ataxia) refer to difficulty controlling the movements of the limbs or body, resulting in clumsiness, stumbling, or an unsteady gait. The cerebellum, which governs balance and coordination, is often affected. Causes include stroke, multiple sclerosis, brain tumors, alcohol intoxication, certain medications, vitamin B12 deficiency, and hereditary conditions. Sudden onset of coordination problems — especially with double vision, slurred speech, or weakness — is a medical emergency: call 911, as it may indicate a cerebellar stroke. Gradual coordination problems should be evaluated promptly. Physical and occupational therapy can help manage symptoms of chronic ataxia effectively.

ICD-10: R27

A copay assistance card—also called a manufacturer coupon, copay card, or savings card—is a benefit offered by pharmaceutical companies to help commercially insured patients afford the out-of-pocket costs of a specific brand-name or specialty drug. When you use the card at the pharmacy, the manufacturer pays some or all of your copay, coinsurance, or deductible contribution for that medication. These cards can dramatically reduce your immediate costs, but there is a critical catch: on ACA marketplace plans, amounts paid by a copay card may not count toward your plan's out-of-pocket maximum, leaving you with higher costs later in the year. Copay cards are generally not valid for patients with Medicare, Medicaid, or CHIP. Always ask your pharmacist and insurance company how your plan handles copay assistance.

A copayment is a fixed dollar amount you pay for a covered healthcare service, such as a doctor visit or prescription, at the time of service. Copays are set by your insurance plan and do not count toward your deductible in some plans. Common copays include $20–$40 for a primary care visit and $50–$100 for a specialist. After meeting your deductible, copays often remain in effect until you reach your out-of-pocket maximum.

COPD is a progressive lung disease that makes it increasingly difficult to breathe. It includes chronic bronchitis and emphysema, most commonly caused by long-term cigarette smoking or exposure to irritants like air pollution or occupational dust. Symptoms include a persistent cough with mucus, wheezing, shortness of breath, and frequent respiratory infections. There is no cure, but treatment with bronchodilator inhalers, corticosteroids, pulmonary rehabilitation, and in some cases supplemental oxygen can slow progression and significantly improve quality of life. Quitting smoking is the most important step to slow the disease.

ICD-10: J44

The cornea is the clear, dome-shaped surface that covers the front of your eye. It acts like a window, allowing light to enter the eye. The cornea also does about two-thirds of the eye's focusing work, bending light so it lands properly on the retina at the back of the eye. Unlike most tissues in the body, the cornea has no blood vessels — it gets nutrients from tears and the fluid inside the eye. This makes it transparent. Diseases or injuries that scratch or cloud the cornea can blur your vision. LASIK surgery reshapes the cornea to correct nearsightedness, farsightedness, and astigmatism. Corneal transplants replace a damaged cornea with a donor one.

The coronary arteries are the blood vessels that supply the heart muscle itself with oxygen and nutrients. The heart cannot use blood that is simply passing through its chambers — it needs its own dedicated supply. Two main coronary arteries — the left and the right — branch off the aorta just above the aortic valve and wrap around the heart. When fatty deposits called plaque build up inside a coronary artery and narrow it, the heart muscle may not get enough blood, causing chest pain called angina. If a plaque ruptures and completely blocks the artery, the result is a heart attack. Stents or bypass surgery are common treatments to restore blood flow.

Coronary artery disease (CAD) occurs when fatty deposits called plaque build up inside the arteries that supply blood to the heart. This buildup, called atherosclerosis, narrows the arteries and reduces blood flow to the heart muscle. Reduced blood flow can cause chest pain (angina), shortness of breath, or a heart attack if an artery becomes fully blocked. CAD is the most common type of heart disease. Risk factors include high blood pressure, high cholesterol, smoking, diabetes, and family history. Treatment includes lifestyle changes, medications, and procedures such as stenting or bypass surgery.

ICD-10: I25

Coronary bypass surgery, also called coronary artery bypass grafting (CABG), reroutes blood flow around blocked or narrowed coronary arteries to improve blood supply to the heart muscle. A blood vessel harvested from the leg, chest, or arm is used to create a new pathway bypassing the blockage. The surgery is performed under general anesthesia and requires opening the chest. A heart-lung machine may temporarily take over heart and lung function during the procedure. Recovery involves a hospital stay of four to seven days and several weeks of cardiac rehabilitation. Most patients experience significant reduction in chest pain and improved heart function afterward.

Corticosteroids are powerful anti-inflammatory medications that mimic hormones produced by the adrenal glands. They reduce inflammation and suppress the immune system. They are used to treat conditions such as asthma, allergic reactions, rheumatoid arthritis, inflammatory bowel disease, and skin conditions. Common corticosteroids include prednisone, methylprednisolone, dexamethasone, and hydrocortisone. They come in many forms: pills, inhalers, skin creams, eye drops, and injections. Short-term use is generally safe, but long-term use can cause side effects including weight gain, elevated blood sugar, bone thinning, and increased infection risk. Never stop corticosteroids suddenly after prolonged use — your doctor should taper the dose.

Cost sharing refers to the portion of covered health care costs that you, the patient, pay out of pocket rather than your insurer. It includes your deductible, copays, and coinsurance. For example, if your plan has a $1,000 deductible and 20% coinsurance, you pay the first $1,000 of covered services and then 20% of costs after that until you reach your out-of-pocket maximum. Cost sharing encourages patients to be thoughtful about health care use and is a key factor when comparing plans. ACA marketplace plans offer cost-sharing reduction subsidies to qualifying lower-income enrollees, which lower deductibles and copays on Silver-tier plans.

A cost-based fee is a payment method used by Medicare and Medicaid to reimburse certain federally qualified health centers (FQHCs) and rural health clinics (RHCs). Instead of paying a fixed fee for each service, Medicare and Medicaid reimburse these facilities based on their actual, reasonable costs of providing care. This approach ensures that safety-net clinics serving low-income and rural populations receive enough funding to cover their operating expenses, even if the patient mix includes many uninsured or underinsured individuals. For patients, receiving care at a federally qualified health center means services are available on a sliding-fee scale based on income, and the facility is structured to serve those who might not afford care elsewhere.

A cost-sharing reduction (CSR) is a federal subsidy that lowers the amount eligible lower-income individuals and families pay out-of-pocket when they use health insurance. CSRs reduce deductibles, copays, coinsurance, and out-of-pocket maximums. To qualify, you must enroll in a Silver-tier plan through the Health Insurance Marketplace and have a household income between 100% and 250% of the federal poverty level. CSRs are applied automatically when you enroll in a qualifying Silver plan — you do not have to apply separately. They are distinct from premium tax credits, which reduce your monthly premium.

A cough is a reflex action that clears your airway of mucus, irritants, or foreign particles. Occasional coughing is normal and protective. A persistent cough lasting more than three weeks should be evaluated by a doctor. Common causes include respiratory infections, allergies, asthma, GERD, postnasal drip, and smoking. Some blood pressure medications can also cause a chronic dry cough. Seek care promptly if your cough produces blood, is accompanied by chest pain or high fever, causes you to vomit, or if you have significant weight loss or night sweats alongside coughing.

ICD-10: R05

The coverage gap—informally known as the 'donut hole'—is a phase of Medicare Part D prescription drug coverage where you temporarily face higher drug costs. It begins after you and your plan together have spent a set total amount on covered drugs in a year. Until 2024, beneficiaries in the gap paid a larger share of drug costs; starting in 2025, the Inflation Reduction Act largely closes the donut hole by capping Medicare beneficiaries' annual out-of-pocket drug costs. After reaching the catastrophic coverage threshold, Medicare pays a very high percentage of costs. Generic drugs are typically cheaper during the gap phase. Copay assistance cards from drug manufacturers generally cannot be used by Medicare beneficiaries to fill this gap.

Under the federal HIPAA Privacy Rule, a covered entity is one of three types of organizations that are directly required by law to protect your private health information: health plans (including insurers, HMOs, Medicare, and Medicaid), healthcare clearinghouses (companies that process billing transactions), and most healthcare providers who transmit health information electronically—including doctors, dentists, hospitals, pharmacies, and nursing homes. Covered entities must follow strict rules about who can see your health records, how they must safeguard data, and what privacy notice they must give you. If you believe a covered entity has violated your privacy rights, you can file a complaint with the HHS Office for Civil Rights at no cost.

A covered service is any medical service, procedure, drug, or supply that your health insurance plan will pay for, at least in part, when medical necessity and other plan requirements are met. Covered services are described in your plan documents, including the Summary of Benefits and Coverage. Common covered services include preventive care, hospitalization, emergency services, prescription drugs, and lab tests. However, coverage may depend on meeting your deductible, obtaining prior authorization, using in-network providers, or satisfying other conditions. Always verify with your insurer that a specific service is covered before receiving care to avoid unexpected bills.

COVID-19 is a respiratory illness caused by the SARS-CoV-2 coronavirus. Symptoms range from mild, such as fever, cough, and fatigue, to severe, including difficulty breathing, chest pain, and low oxygen levels. Some people develop serious complications including pneumonia and organ failure. Treatment depends on severity and may include antiviral medications, supplemental oxygen, or hospitalization. Vaccination significantly reduces the risk of severe illness. Some people experience persistent symptoms for weeks or months after infection, a condition called Long COVID. Good hand hygiene and staying up to date on vaccines help prevent spread.

ICD-10: U07

Continuous Positive Airway Pressure (CPAP) therapy is the standard treatment for obstructive sleep apnea. A CPAP machine delivers a steady stream of pressurized air through a mask worn over the nose or nose and mouth while you sleep. The air pressure keeps your airway open, preventing the repeated breathing pauses that characterize sleep apnea. Over time, CPAP therapy reduces daytime sleepiness, lowers blood pressure, decreases cardiovascular risk, and improves overall sleep quality. A sleep study (polysomnogram) is usually required to diagnose sleep apnea and determine the correct pressure setting for your machine.

A Current Procedural Terminology (CPT) code is a standardized five-digit numeric code maintained by the American Medical Association that describes a specific medical service, diagnostic procedure, or surgical operation. Every service billed to an insurance company or government program must include at least one CPT code so the payer understands exactly what was done. For example, a routine office visit might use code 99213, while a knee arthroscopy would have a different code. Your Explanation of Benefits should list the CPT codes for all services billed. If you see an unfamiliar code on your bill, look it up on the AMA website or ask your provider's billing department what it represents—incorrect CPT codes are a common source of billing errors and claim denials.

Cramping is a sudden, involuntary, and often painful muscle contraction or tightening. It can occur in skeletal muscles (such as a leg cramp at night) or in smooth muscles of the digestive tract or uterus. Abdominal cramping often accompanies diarrhea, irritable bowel syndrome, or menstruation. Muscle cramps may be caused by dehydration, electrolyte imbalances, overuse, or poor circulation. Cramps usually resolve quickly on their own; stretching, massage, heat, and staying hydrated can help. See a provider if cramps are severe, frequent, persist for a long time, occur in the chest, or are accompanied by swelling, redness, or skin changes in the affected area.

A creatinine test measures the level of creatinine — a waste product made when your muscles break down a substance called creatine — in your blood or urine. Healthy kidneys filter creatinine out of the blood and send it into the urine. When kidneys are not working well, creatinine builds up in the blood. A blood sample is drawn from a vein in your arm. Normal blood creatinine is roughly 0.7–1.2 mg/dL in adults, though it varies by age, sex, and muscle mass. Doctors order this test to evaluate kidney function, diagnose kidney disease, and monitor patients taking medications that can affect the kidneys.

A credit bureau—also called a credit reporting agency—is a company that collects, maintains, and sells financial information about individuals. The three major national credit bureaus in the United States are Equifax, Experian, and TransUnion. They compile data from lenders, collection agencies, and public records to create credit reports that lenders use to decide whether to extend credit and at what interest rate. Unpaid medical bills sent to collections have historically appeared on credit reports and lowered credit scores, though federal and state rules have increasingly restricted this practice. You are entitled to a free credit report from each bureau every 12 months at AnnualCreditReport.com, and you have the right to dispute inaccurate medical debt entries. The CFPB oversees credit bureaus and handles consumer complaints.

A credit report is a detailed record of your borrowing history and financial behavior, compiled by credit bureaus such as Equifax, Experian, and TransUnion. It includes your open and closed credit accounts, payment history, amounts owed, length of credit history, and any negative items such as collections, bankruptcies, or judgments. Medical debt that has been sent to collections may appear on your credit report and negatively affect your credit score, though major credit bureaus have begun removing paid medical collections and smaller medical debts under certain thresholds. You are entitled to a free report from each bureau once every 12 months at AnnualCreditReport.com. Review your report regularly to catch errors—particularly medical debt entries—and dispute inaccuracies in writing.

Creditable coverage refers to prescription drug or health coverage that is at least as good as Medicare's standard coverage for the same benefit type. The concept matters most for Medicare Part D drug coverage: if you delay enrolling in Part D but had creditable drug coverage elsewhere—such as from an employer plan, TRICARE, or the VA—you will not face a late enrollment penalty when you eventually join. Your employer or plan must send you a written notice each year stating whether your drug coverage is creditable. If you receive a notice saying your coverage is not creditable, you should seriously consider enrolling in Medicare Part D during your next special or open enrollment period to avoid a permanent penalty.

Crisis intervention is immediate, short-term support provided to people experiencing an acute mental health crisis — such as thoughts of suicide, a psychotic episode, or an overwhelming emotional emergency. The goal is to stabilize the person, ensure safety, and connect them to ongoing care. In the US, crisis services include the 988 Suicide and Crisis Lifeline (call or text 988), mobile crisis teams that can respond in the community, and crisis stabilization units as an alternative to emergency rooms. Many communities also offer walk-in crisis centers. Crisis intervention is not the same as long-term treatment — it is the first step toward connecting with appropriate ongoing mental health care.

A crisis respite center is a short-term, community-based residential facility that provides a safe, calming environment for individuals who are experiencing a mental health or psychiatric crisis but do not need the level of care provided in a hospital emergency room or inpatient psychiatric unit. These centers offer peer support, counseling, basic needs, and stabilization services, typically for up to 5 to 7 days. They are designed as a voluntary, less restrictive alternative to emergency hospitalization, helping people stabilize and connect with outpatient mental health services. Mental health parity law requires many insurance plans to cover crisis respite services at the same level as comparable medical services. Coverage varies by plan, so confirm benefits before seeking care.

A crisis stabilization unit (CSU) is a short-term, 24-hour residential facility that provides intensive psychiatric observation, evaluation, and treatment for individuals experiencing an acute mental health emergency. CSUs serve as an alternative to—or step-down from—a traditional psychiatric inpatient hospitalization. They typically offer structured programming, medication evaluation, and discharge planning, with stays commonly lasting 3 to 5 days. CSUs are designed to safely stabilize patients and connect them with longer-term community mental health services. Under mental health parity law, insurance plans that cover comparable medical or surgical care must also cover CSU services at equivalent benefit levels. Prior authorization may be required. If you or someone you know is in crisis, call or text 988 (Suicide and Crisis Lifeline).

Crohn's disease is a chronic inflammatory bowel disease that causes inflammation in the digestive tract, which can lead to abdominal pain, severe diarrhea, fatigue, weight loss, and malnutrition. The inflammation can affect any part of the digestive tract from the mouth to the anus, but most commonly affects the end of the small intestine and the beginning of the colon. The exact cause is unknown but involves an abnormal immune response and genetic factors. There is no cure, but treatment with anti-inflammatory drugs, immune-suppressing medications, and biologics can help control symptoms, reduce flare-ups, and achieve long-term remission.

ICD-10: K50

A crossover claim is a medical claim that is automatically forwarded from Medicare (the primary payer) to Medicaid (the secondary payer) after Medicare has processed it. This applies to patients who are dual-eligible — covered by both Medicare and Medicaid. The crossover process is designed to cover any remaining cost-sharing amounts that Medicare did not pay, such as deductibles and coinsurance, so that dual-eligible patients owe little or nothing out-of-pocket. Most crossover claims are transmitted electronically without requiring extra action from the patient or provider.

Croup is a viral infection of the upper airway that causes a distinctive barking cough, hoarse voice, and a high-pitched noisy breathing sound called stridor when your child inhales. It most commonly affects children under 5, usually in fall and winter. The swelling narrows the windpipe, making breathing difficult — symptoms are often worse at night. Mild croup can be managed at home with cool night air or steam and keeping your child calm. Your child's doctor may prescribe a dose of corticosteroids (such as dexamethasone) to reduce airway swelling. Difficulty breathing, blue lips, or drooling require emergency care.

ICD-10: J05

Cryotherapy uses extreme cold — typically liquid nitrogen — to freeze and destroy abnormal or unwanted tissue. Doctors apply it directly to skin lesions such as warts, actinic keratoses, and certain skin cancers. It is also used internally to treat abnormal cells in the cervix (cryosurgery), and in oncology to freeze tumors in organs such as the liver, prostate, or kidney. The procedure is usually quick, done in a clinic or office setting, and local anesthesia may be used. The treated area typically blisters, scabs, and heals over days to weeks. Multiple sessions may be needed for complete treatment.

CT angiography uses a CT scanner and an intravenous contrast dye to produce detailed images of blood vessels and evaluate for blockages, aneurysms, or structural problems. The dye is injected through a vein in your arm, and images are captured as it flows through your vessels. You will lie on a table that slides through the scanner while the machine rotates around you taking rapid images. The scan is fast, usually five to fifteen minutes. You may feel a warm flush when the contrast is injected. Kidney function is checked before the test because the contrast dye is filtered through the kidneys. You should fast for several hours beforehand. CTA is commonly used to evaluate coronary arteries, pulmonary vessels, and the aorta.

A CT scan uses X-rays taken from many angles around your body to create detailed cross-sectional images. You will lie on a motorized table that slides through a large doughnut-shaped machine called a gantry. The machine rotates around you, taking multiple images quickly. The scan usually takes 10 to 30 minutes. You may receive an intravenous contrast dye to make certain structures more visible; if so, you should avoid food a few hours beforehand and mention any kidney problems or allergies. You may feel a warm flushing sensation if contrast is used. CT scans provide much more detail than regular X-rays and are used to evaluate organs, blood vessels, and internal injuries.

Cyanosis is a bluish or purplish discoloration of the skin, lips, or fingertips caused by low oxygen levels in the blood. It is a serious warning sign that the body is not getting enough oxygen. Causes include severe asthma attacks, pneumonia, heart failure, pulmonary embolism, and congenital heart defects. Central cyanosis affects the lips and tongue, while peripheral cyanosis appears in the fingers and toes. Cyanosis in adults or children should be treated as a medical emergency. Call 911 immediately if you or someone else shows signs of cyanosis, especially with difficulty breathing or chest pain.

ICD-10: R23

A cystoscopy is a procedure that allows your doctor to look inside your bladder and urethra using a thin, flexible tube with a camera called a cystoscope. The scope is gently inserted through the urethra. Local anesthesia jelly is applied to minimize discomfort. You may feel some pressure or a mild burning sensation during the procedure. The exam typically takes 5 to 20 minutes. Your doctor uses this test to look for bladder tumors, stones, infections, or the cause of blood in the urine. You may notice some urinary burning or light bleeding for a day or two afterward. Drinking plenty of fluids helps flush the urinary tract. Some procedures are done under general or spinal anesthesia.

The date of service (DOS) is the specific calendar date on which a medical service, procedure, exam, or prescription was provided to a patient. It is one of the most critical data points on any insurance claim or medical bill. Insurers use the date of service to verify that coverage was active on that day, to apply the correct plan-year deductibles and out-of-pocket amounts, and to enforce timely filing deadlines—the window within which a provider must submit a claim. If your date of service falls outside your coverage period or after a lapse in enrollment, a claim may be denied. Always check that the date of service on your bill matches your actual appointment or procedure date, as billing errors here are common and can cause unnecessary denials or duplicate charges.

Dialectical Behavior Therapy (DBT) is an evidence-based form of cognitive behavioral therapy originally developed for people with borderline personality disorder but now used for a range of conditions including depression, PTSD, eating disorders, and substance use. DBT focuses on four core skill areas: mindfulness, emotional regulation, distress tolerance, and interpersonal effectiveness. A full DBT program typically includes weekly individual therapy sessions, a weekly skills training group, and phone coaching between sessions. DBT was developed to help people build a life worth living by learning practical skills to manage overwhelming emotions and improve relationships. It is one of the most thoroughly researched psychotherapy approaches. Ask your insurer for in-network DBT providers.

The DEA Schedule is a classification system the Drug Enforcement Administration uses to group controlled substances into five categories based on their accepted medical use and potential for abuse. Schedule II drugs, such as opioids and Adderall, have the highest accepted-use abuse potential. Schedules III through V have progressively lower abuse potential. Schedule I drugs, such as heroin, have no accepted medical use. Your medication's schedule affects how many refills are permitted, how many days' supply a pharmacy can dispense at once, and how strictly the prescription is monitored by federal and state authorities.

A debt collector is a company or individual hired to recover unpaid debts, including medical bills, on behalf of the original creditor or after purchasing the debt at a discount. Debt collectors are regulated by the Fair Debt Collection Practices Act (FDCPA), which prohibits harassment, false statements, and unfair practices. Under the FDCPA, collectors must send you a written validation notice within five days of first contacting you, and you have 30 days to dispute the debt in writing and request verification. Collectors cannot call before 8 a.m. or after 9 p.m., cannot call your workplace if you tell them not to, and cannot threaten legal action they do not intend to take. If a collector violates these rules, you can file a complaint with the CFPB or your state attorney general.

Debt validation is your legal right under the Fair Debt Collection Practices Act (FDCPA) to request written proof that a debt is accurate and that the collection agency has the legal authority to collect it from you. When a debt collector first contacts you, they must send a written validation notice within five days. You then have 30 days to send a written dispute and request for verification. Once you request validation, the collector must stop collection activities until it provides the required documentation—including the name of the original creditor and the amount owed. For medical debt, validation can reveal billing errors, insurance processing mistakes, or even debts that are too old to be legally collected (past the statute of limitations). Always send your dispute by certified mail with return receipt to create a paper trail.

Decongestants are medications that relieve nasal and sinus congestion by narrowing blood vessels in the nasal passages, which reduces swelling and mucus. They are commonly used for colds, allergies, and sinusitis. Pseudoephedrine (Sudafed) and phenylephrine are the most common. Pseudoephedrine is kept behind the pharmacy counter due to regulations. Nasal spray decongestants (like oxymetazoline) work quickly but should not be used for more than three consecutive days, as overuse can cause rebound congestion. Decongestants can raise blood pressure and heart rate — people with hypertension, heart disease, or thyroid problems should consult their doctor before use.

A deductible is the amount you pay out of pocket for covered health services before your insurance begins to share costs. For example, with a $1,500 deductible, you pay the first $1,500 of covered services each year before coinsurance or lower copays kick in. Preventive care is typically covered before the deductible under the ACA. Family plans may have separate individual and family deductibles. High-deductible health plans (HDHPs) pair with HSAs for tax savings.

Deemed exhaustion is a legal status that allows you to skip your health plan's internal appeal process and request external review immediately, when your insurer has failed to follow required federal or state appeal rules. Under the ACA, health plans must process appeals within strict timeframes and follow specific procedural rules. If a plan violates these requirements—for example, by missing a decision deadline, failing to provide adequate notice, or not having a proper appeals process in place—you are deemed to have exhausted internal remedies even without completing them. This lets you go directly to an Independent Review Organization (IRO) for an external review. Deemed exhaustion is an important patient protection that prevents insurers from delaying or denying external review through procedural failures.

Deep vein thrombosis (DVT) is a blood clot that forms in a deep vein, usually in the leg. The clot partially or completely blocks blood flow through the vein. Symptoms include leg pain, swelling, warmth, and redness, though some clots cause no symptoms. DVT is dangerous because the clot can break loose and travel to the lungs, causing a pulmonary embolism, which can be life-threatening. Risk factors include prolonged immobility, recent surgery, pregnancy, cancer, and clotting disorders. Treatment typically involves blood-thinning medications (anticoagulants) to prevent the clot from growing and to reduce the risk of pulmonary embolism.

ICD-10: I82

Deferred interest is a financing arrangement commonly offered by medical credit cards—such as CareCredit—and hospital payment plan programs. Under a deferred-interest offer, interest accumulates on your balance during a promotional period (often 12 to 24 months), but it is waived if you pay off the entire balance before the deadline. If you have any remaining balance at the end of the promotional period, all of the accumulated interest—sometimes years' worth at rates of 26% or higher—is added to your balance at once. This retroactive interest charge can significantly increase what you owe. It is different from a true 0% APR offer. Always read the fine print before signing up for medical financing, and be sure you can realistically pay off the full balance before the promotional period ends.

Defibrillation is the delivery of a controlled electric shock to the heart to stop a dangerous abnormal heart rhythm such as ventricular fibrillation (chaotic, ineffective heartbeat) or ventricular tachycardia and allow the heart to return to a normal rhythm. It is performed using a defibrillator—either an automated external defibrillator (AED) found in public places or a hospital-grade device used by medical staff. Defibrillation is a life-saving emergency procedure. In a Code Blue situation, staff may defibrillate multiple times. Bystanders can also use an AED before emergency services arrive, as early defibrillation greatly improves survival from sudden cardiac arrest.

Dehydration occurs when your body loses more fluid than you take in, impairing normal bodily functions. Causes include insufficient fluid intake, vomiting, diarrhea, fever, excessive sweating, and certain medications such as diuretics. Signs include dark urine, dry mouth, headache, dizziness, fatigue, and decreased urination. Severe dehydration can cause confusion, rapid heartbeat, and fainting and is a medical emergency. Older adults, young children, and people with chronic illnesses are at higher risk. Mild dehydration is treated with oral fluids and electrolyte drinks. Moderate to severe dehydration may require intravenous fluids in a healthcare setting.

ICD-10: E86

Delirium is a sudden, serious change in mental state marked by confusion, disorientation, impaired attention, and sometimes hallucinations. It develops rapidly, often over hours or days, and can fluctuate throughout the day. It is common in hospitalized older adults and is triggered by serious infection, high fever, medication side effects, surgery, dehydration, or withdrawal from alcohol or drugs. Delirium is a medical emergency. Family members often notice behavioral changes first. Treatment focuses on identifying and addressing the underlying cause. Early recognition is critical because untreated delirium can worsen outcomes and lead to prolonged confusion or cognitive decline.

ICD-10: F05

A denial code is a standardized alphanumeric code that appears on an Explanation of Benefits (EOB), remittance advice, or claim rejection notice to indicate why an insurance claim was denied, reduced, or adjusted. Common denial codes include CO-4 (incorrect procedure code), CO-50 (service not covered), PR-96 (non-covered charge), and CARC/RARC codes used by Medicare. Each code corresponds to a specific reason for non-payment. Understanding the denial code on your EOB is the essential first step in deciding whether to appeal a denial. Many denials result from administrative errors—such as a wrong billing code or missing information—that can be corrected and resubmitted. Ask your provider's billing office to identify the denial code and determine whether a corrected claim or appeal is the best path forward.

A denial notice is a written communication from your health insurance company or government health program stating that a claim, coverage request, or prior authorization has been denied—either fully or partially. Federal law requires that denial notices include the specific reason for the denial, the denial code used, the clinical rationale if the denial is based on medical necessity, and clear information about your right to appeal and the steps and deadlines to do so. Do not discard a denial notice; it is the starting document for any appeal you wish to file. Read it carefully to understand the reason for denial, collect relevant medical records and your doctor's documentation, and submit your appeal in writing within the stated deadline—typically 180 days from the denial date.

A dependent is a family member listed on your health insurance policy who receives coverage through your plan rather than their own. Typically this includes spouses, domestic partners, and children under age 26—even if married, living separately, or not enrolled in school. Some plans extend dependent status to disabled adult children beyond age 26 if the disability began before that age. Grandchildren, nieces, and other relatives generally do not qualify unless they are legal tax dependents. Adding or removing a dependent usually triggers a special enrollment period. Your employer or Marketplace plan requires supporting documents, such as a birth certificate or marriage license, to verify the relationship before coverage begins.

Depression is a common medical condition that affects how you feel, think, and manage daily life. It goes beyond ordinary sadness and can cause persistent low mood, loss of interest in activities you used to enjoy, changes in sleep and appetite, low energy, and difficulty concentrating. Depression is not a personal weakness — it is a health condition with effective treatments. In the US, it is usually treated with therapy, medication, or a combination of both. You can access care through your primary care provider, a psychiatrist, or a therapist. Contact your insurance's behavioral health line to find in-network providers.

ICD-10: F32

The dermis is the middle layer of your skin, located directly below the epidermis (outer layer) and above the deeper subcutaneous tissue. It is the thickest skin layer and contains collagen and elastin fibers that give skin its strength, firmness, and ability to stretch and bounce back. The dermis also houses hair follicles, sweat glands, oil glands, nerve endings that sense touch and pain, and blood vessels that nourish the skin. Conditions that affect the dermis include eczema, psoriasis, and dermatitis. Burns that reach the dermis are classified as second-degree burns and may cause blistering and scarring if not treated properly.

Under the HIPAA Privacy Rule, the designated record set is the collection of records a covered entity—such as a hospital, clinic, or health plan—maintains about you. It includes your medical records, billing records, clinical lab results, and health plan enrollment and payment information. You have a legal right to inspect these records and request amendments if you believe information is incorrect or incomplete. The covered entity must respond within 30 days and may extend by another 30 days with written notice. Psychotherapy notes held separately by a therapist and records compiled for litigation are generally excluded. Reviewing your designated record set regularly helps catch errors before they affect your care.

Developmental milestones are skills and behaviors that most children reach by certain ages, including physical (rolling over, walking), language (babbling, saying words), social (smiling, playing with others), and cognitive (problem-solving) skills. The CDC's milestone checklists give typical age ranges for each milestone — for example, most babies say their first word by 12 months. Missing multiple milestones may signal a developmental delay that warrants evaluation. Every child develops at their own pace, but significant or persistent delays should be discussed with your pediatrician so early intervention services can be offered if needed.

ICD-10: F88

A DEXA scan measures the density of your bones to check for osteoporosis or low bone mass. You will lie on a padded table while a scanning arm passes slowly over your body, typically focusing on your hip and lower spine. The test uses two low-dose X-ray beams to measure how dense your bones are. It is completely painless and usually takes 10 to 30 minutes. No injection or special preparation is needed, but you should avoid calcium supplements for 24 hours before the test. You should wear comfortable, metal-free clothing. Results are given as a T-score, which compares your bone density to that of a healthy young adult.

Diabetic ketoacidosis (DKA) is a serious and potentially life-threatening complication of diabetes, most often type 1 diabetes. It occurs when the body has very little or no insulin, causing blood sugar to rise very high. Without insulin, cells cannot use sugar for energy, so the body breaks down fat rapidly, producing acidic compounds called ketones that build up in the blood. Symptoms include extreme thirst, frequent urination, nausea, vomiting, abdominal pain, fruity-smelling breath, and confusion. DKA requires immediate emergency medical treatment with intravenous fluids, insulin, and electrolyte replacement. It can be triggered by illness, missed insulin doses, or newly undiagnosed diabetes.

ICD-10: E10

A diagnosis code identifies a patient's medical condition on insurance claims and clinical records. In the United States, diagnosis codes follow the ICD-10-CM system. Every claim submitted to a US insurer must include at least one diagnosis code that justifies the medical necessity of the service. Codes are assigned by the treating provider based on the documented diagnosis, not symptoms alone. Incorrect or unsupported diagnosis codes are a common cause of claim denials.

The diaphragm is a large dome-shaped muscle that sits just beneath your lungs and separates your chest from your abdomen. It is the most important muscle for breathing. When you inhale, the diaphragm contracts and flattens, pulling air down into your lungs. When you exhale, it relaxes and rises back into its dome shape, pushing air out. Hiccups happen when the diaphragm spasms involuntarily. The diaphragm also has openings that allow the esophagus, aorta, and major blood vessels to pass through it. A hiatal hernia occurs when part of the stomach pushes through the opening in the diaphragm meant for the esophagus.

Diarrhea means having loose, watery bowel movements three or more times in a single day. It is one of the most common digestive complaints and is usually caused by a viral or bacterial infection, food intolerance, medications such as antibiotics, or inflammatory bowel disease. Most cases of acute diarrhea resolve on their own within one to two days with rest and fluids. Seek care if diarrhea lasts more than two days in an adult or 24 hours in a child, if there is blood or mucus in the stool, if fever is high, or if signs of dehydration appear such as dizziness, dry mouth, or very dark urine.

ICD-10: R19

Discharge refers to fluid or secretions coming from a body opening or wound that differ from what is normal. Examples include nasal discharge, eye discharge, nipple discharge, vaginal discharge, urethral discharge, or drainage from a wound or ear. The significance depends on the color, consistency, odor, and location. Unusual discharge that is yellow, green, bloody, or foul-smelling often indicates infection. Nipple discharge in non-breastfeeding individuals should always be evaluated. New or changed discharge from any site warrants medical assessment to determine if infection, inflammation, hormonal changes, or other underlying conditions require treatment.

Discharge planning is the process of preparing a patient to safely leave the hospital and continue recovering at home or at another facility. A discharge planner, social worker, or case manager works with you, your family, and your medical team to arrange follow-up appointments, medications, equipment, or transfer to a rehabilitation center or nursing home. It begins soon after admission, not just at the last minute. Ask about your discharge plan early so you have time to arrange transportation, fill prescriptions, and understand any home care instructions. Being discharged means the hospital team believes you are medically stable enough to leave.

Disenrollment is the process of leaving or being removed from a health insurance plan. It may happen voluntarily—such as when you switch plans during open enrollment—or involuntarily, when you lose a job, move out of the plan's service area, fail to pay premiums, or no longer meet eligibility requirements. If you are involuntarily disenrolled from Medicaid because your income rose above the threshold, you may qualify for a special enrollment period to find new coverage. Disenrollment from Medicare Advantage returns you to Original Medicare, but with limited windows for additional changes. Always confirm your disenrollment date in writing so you can arrange replacement coverage and avoid a gap.

In telehealth, the distant site is the physical location where the licensed healthcare provider is situated when delivering care remotely. For example, a physician in Chicago is at the distant site when conducting a video visit with a patient in rural Montana (the originating site). Medicare and most insurers require the distant-site provider to hold a valid license in the state where the patient is located. Medicare covers a growing list of services at the distant site, including mental health visits, chronic care management, and specialist consultations. Confirming that your telehealth provider's distant site qualifies under applicable rules helps prevent unexpected claim denials. Compare this with originating site, which is where the patient is.

Diuretics, often called water pills, help the body remove excess salt and water through urine. This reduces fluid buildup and lowers blood pressure. They are used to treat high blood pressure, heart failure, kidney disease, and edema (swelling). Common diuretics include furosemide (Lasix), hydrochlorothiazide, and spironolactone. Because they increase urination, it is best to take them in the morning to avoid nighttime bathroom trips. Diuretics can lower potassium levels, so your doctor may check blood tests regularly or recommend a potassium-rich diet. Stay well hydrated but do not overdo fluids unless instructed.

Diverticulitis occurs when small pouches called diverticula that have formed in the walls of the colon become inflamed or infected. These pouches commonly form in areas of weakness in the colon wall, often later in life. Symptoms include sudden abdominal pain usually in the lower left side, fever, nausea, vomiting, and changes in bowel habits. Mild cases are treated with antibiotics, rest, and a clear liquid diet. Severe cases or complications such as abscess, perforation, or fistula may require hospitalization and surgery. A high-fiber diet after recovery may help prevent future episodes. Colonoscopy is recommended after recovery to rule out other conditions.

ICD-10: K57

Diverticulosis is a condition in which small pouches (diverticula) form in the walls of the colon, usually in the lower left section. It is extremely common, affecting about half of all people over age 60 in the US. Most people with diverticulosis have no symptoms and the condition is often found incidentally during colonoscopy. A low-fiber diet is thought to contribute to its development. When the pouches become inflamed or infected, the condition is called diverticulitis, which can cause significant abdominal pain, fever, and changes in bowel habits. Treatment of diverticulosis focuses on a high-fiber diet.

ICD-10: K57

A feeling of lightheadedness, unsteadiness, or being off-balance without a sense that the room is spinning. It may occur when you stand up too quickly, become dehydrated, skip meals, or take certain medications. Dizziness is also linked to inner ear problems, low blood pressure, anemia, and anxiety. It is usually temporary and not dangerous on its own. However, dizziness that is sudden, severe, or accompanied by chest pain, shortness of breath, fainting, slurred speech, or weakness on one side of the body is a medical emergency — call 911 immediately. Keep a log of episodes to help your doctor identify the cause.

ICD-10: R42

Durable Medical Equipment (DME) refers to medical devices prescribed by a physician for repeated use in the home to treat a medical condition. Examples include wheelchairs, walkers, hospital beds, oxygen equipment, CPAP machines, blood glucose monitors, and prosthetics. Medicare Part B covers DME when it is medically necessary and prescribed by a doctor. Private insurance DME coverage varies; prior authorization is commonly required. DME must be purchased from a Medicare-approved supplier for Medicare coverage to apply.

A Do Not Resuscitate (DNR) order is a medical order placed in your hospital chart that instructs healthcare staff not to perform CPR (cardiopulmonary resuscitation) if your heart stops or you stop breathing. A DNR must be ordered by a physician, usually based on your wishes or those of your legally authorized representative. Having a DNR does not mean you will receive less care overall — you will still receive comfort measures, pain relief, and other treatments. Some people prefer this choice when they have a terminal illness or feel that CPR would not match their goals. Discuss DNR options with your doctor and family.

A Doppler ultrasound uses high-frequency sound waves to measure the speed and direction of blood flow through your blood vessels and heart. Unlike a regular ultrasound that shows organ structure, Doppler technology detects movement — specifically moving red blood cells — and translates that into color maps or waveforms on a screen. Gel is applied to your skin and a transducer is placed over the area to be examined. The test is painless and takes 30 to 60 minutes. It is used to check for blood clots in the legs, assess blood flow to the fetus during pregnancy, evaluate carotid artery disease, and monitor blood flow after surgery. No radiation is used. Results are available shortly after the test.

Dosage refers to the specific amount of medication you take and how often you take it, as directed on your prescription or by your healthcare provider. Your prescription label will state the dose amount, such as 10 milligrams, and the schedule, such as twice daily. Taking the correct dosage is critical because too little may not treat your condition effectively, while too much can cause serious side effects or toxicity. Dosages are often individualized based on your age, weight, kidney and liver function, and response to the medication. Never change your dosage without first talking to your doctor or pharmacist.

Double vision (diplopia) means seeing two images of a single object. It may occur in one eye (monocular) or both eyes together (binocular). Monocular double vision often results from astigmatism, cataracts, or corneal irregularities. Binocular double vision — which disappears when one eye is closed — may indicate nerve or muscle problems affecting eye movement, including stroke, multiple sclerosis, aneurysm, or a brain tumor. Sudden double vision, especially with headache, pain behind the eye, drooping eyelid, or dizziness, is a medical emergency. Call 911 immediately. If double vision develops gradually, see an eye specialist or neurologist promptly for evaluation.

ICD-10: H53

Down syndrome is a genetic condition caused by the presence of an extra copy of chromosome 21, resulting in intellectual disability, distinctive physical features, and sometimes other health problems including heart defects and thyroid issues. It is the most common chromosomal condition in the US. Life expectancy has increased dramatically to over 60 years for many individuals with Down syndrome. Early intervention programs, including physical, speech, and occupational therapy, help children reach their full potential. With proper support, many adults with Down syndrome live semi-independently, hold jobs, and participate fully in their communities.

ICD-10: Q90

Downcoding occurs when an insurance company changes a medical billing code submitted by a provider to a less complex or lower-paying code, reducing the payment the provider receives. Insurers may downcode when they believe the documentation does not support the level of service billed. For patients, downcoding can be confusing because it may change your cost-sharing responsibility if your share is tied to a percentage of the allowed amount. Providers can appeal downcoded claims by submitting additional documentation. Patients may receive an EOB reflecting the adjusted code and a lower allowed amount.

A drug allergy is an immune system reaction to a medication in which your body mistakenly identifies the drug as harmful and mounts a defensive response. Reactions range from mild hives, itching, or skin rash to life-threatening anaphylaxis involving throat swelling, difficulty breathing, and dangerously low blood pressure. A drug allergy differs from a side effect because it involves your immune system and can become more severe with each repeated exposure. Common drug allergies include reactions to penicillin, sulfa antibiotics, aspirin, and certain pain relievers. Always disclose known drug allergies to every healthcare provider and pharmacist before receiving any new medication or procedure.

A drug copay is the fixed dollar amount you pay out of pocket for a prescription medication each time you pick it up, after your insurance plan covers its share of the cost. Copay amounts vary based on your insurance plan, whether the drug is generic or brand-name, and which formulary tier it falls on. For example, your plan might charge $10 for a generic drug and $50 for a brand-name drug. Some plans use coinsurance, where you pay a percentage of the drug cost instead of a flat fee. Manufacturer copay assistance cards or patient assistance programs may reduce or eliminate your copay if you qualify based on income or insurance type.

A drug formulary is a list of prescription medications covered by a health insurance plan. Formularies are organized into tiers, typically ranging from Tier 1 (generic, lowest cost) to Tier 4 or 5 (specialty drugs, highest cost). Drugs not on the formulary require an exception or prior authorization. Formularies change annually and sometimes mid-year; patients should verify their medications are covered before enrolling in a plan or filling a new prescription. Generic substitutes are often available for off-formulary drugs.

A drug interaction occurs when one medication changes the way another medication works in your body. Interactions can make a drug less effective, increase its strength to dangerous levels, or cause unexpected side effects. Interactions can happen between two prescription drugs, between a prescription drug and an over-the-counter medication, or between a drug and certain foods like grapefruit juice. Always tell your pharmacist and doctor about every medication, supplement, vitamin, and herbal product you take so they can screen for harmful interactions before adding a new drug to your regimen.

A drug recall is an action by a manufacturer, typically requested or ordered by the FDA, to remove a medication from the market or from patients' possession because it poses an unacceptable safety risk. Recalls can happen because of contamination, mislabeling, incorrect dosage strength, or newly discovered serious side effects. Your pharmacy or doctor should contact you if a drug you are taking is recalled. Do not stop taking a recalled medication on your own before speaking with your healthcare provider, because stopping certain drugs abruptly can be dangerous. The FDA website lists all active recalls so you can check your medications.

Dry mouth, or xerostomia, is a sensation of insufficient saliva in the mouth. Saliva is essential for chewing, swallowing, speaking, and preventing tooth decay. Common causes include dehydration, breathing through the mouth, anxiety, and medications such as antihistamines, antidepressants, blood pressure drugs, and diuretics. Medical conditions such as Sjögren syndrome, diabetes, and HIV can also reduce saliva production. Dry mouth can cause difficulty swallowing, bad breath, mouth sores, and increased risk of cavities. Chronic dry mouth should be evaluated and managed to protect oral health, often through increased water intake, saliva substitutes, or adjusting medications.

Dry skin, or xerosis, is a condition where the skin loses moisture and becomes rough, flaky, or itchy. It is very common, especially in older adults and during cold or dry weather. Causes include frequent bathing, harsh soaps, low humidity, aging, and medical conditions such as eczema, psoriasis, hypothyroidism, diabetes, and kidney disease. Severe dry skin can crack and become painful or infected. Moisturizers, gentle cleansers, and humidifiers usually help mild cases. If dry skin is persistent, widespread, or accompanied by other symptoms, see a doctor to rule out an underlying medical condition that may require specific treatment.

Dual coverage means you are enrolled in two separate health insurance plans at the same time — for example, your own employer's plan and your spouse's employer plan. Having dual coverage does not mean all your costs are automatically covered twice; instead, the two plans coordinate benefits to determine which pays first and how much each contributes. In some cases, dual coverage can significantly reduce or eliminate your out-of-pocket expenses. You must inform both insurers about the other coverage, and insurers will apply coordination of benefits rules to prevent overpayment beyond your total allowed charges.

Dual-eligible individuals qualify for both Medicare and Medicaid. Medicare is the primary payer; Medicaid pays for costs Medicare does not cover, such as cost-sharing, long-term care, and additional benefits. Dual eligibles include elderly and disabled low-income individuals. They may be enrolled in Dual Eligible Special Needs Plans (D-SNPs) that coordinate both programs. About 12 million Americans are dual-eligible, and they often have complex medical needs. Navigating dual eligibility can be administratively challenging and may require assistance from a benefits counselor.

Your due date is the estimated date when your baby is expected to be born — usually 40 weeks from the first day of your last menstrual period. It is also called the estimated date of delivery (EDD) or estimated date of confinement (EDC). Only about 5% of babies are born exactly on their due date; most arrive within two weeks before or after. Your provider may adjust the due date after an early ultrasound. If you go more than one to two weeks past your due date, your provider may recommend labor induction to reduce risks to you and your baby.

ICD-10: Z34

A dull ache is a steady, low-grade, persistent pain that is less intense than sharp pain but can be constant and wearing. It is often described as a nagging, heavy, or throbbing discomfort. Common sites include the head, back, joints, and muscles. Dull aches may result from muscle tension or overuse, arthritis, chronic infections, nerve compression, or referred pain from organs. Although a dull ache may not feel urgent, ongoing discomfort lasting more than a few days warrants evaluation, especially if it interferes with sleep or daily activities. Keeping track of when the ache occurs and what makes it better or worse helps your provider diagnose the cause.

The duodenum is the first and shortest section of the small intestine, connecting directly to the stomach. It is about ten to twelve inches long and shaped like the letter C. After food leaves the stomach as a semi-liquid, it enters the duodenum where it is mixed with digestive juices from the pancreas and bile from the liver, delivered through the bile duct. These juices neutralize the stomach acid and continue breaking down fats, proteins, and carbohydrates. Peptic ulcers — open sores — can form in the duodenum, causing pain that often improves after eating. The duodenum is a common site for endoscopy and biopsy procedures.

Dysphagia is difficulty swallowing food, liquids, or even saliva. It may feel like food is sticking in the throat or chest, or that swallowing requires extra effort or causes pain. It can arise from problems with the mouth, throat, or esophagus. Common causes include GERD, esophageal strictures, throat infections, neurological conditions such as stroke or Parkinson's disease, and, less commonly, esophageal cancer. Dysphagia that is new, persistent, or worsening should always be evaluated by a doctor. It can lead to poor nutrition, dehydration, aspiration pneumonia, and choking if untreated.

ICD-10: R13

Ear pain is discomfort or aching inside or around the ear. It can feel sharp, dull, or burning, and may be constant or come and go. The most common cause in children and adults is an ear infection (otitis media or otitis externa, also known as swimmer's ear). Other causes include wax buildup, sinus congestion, jaw problems such as TMJ disorder, throat infections, or a ruptured eardrum. Ear pain may also radiate from the jaw, throat, or neck. See a provider if the pain is severe or gets worse, is accompanied by hearing loss, discharge, fever, or dizziness, or does not improve within a day or two.

The eardrum, also called the tympanic membrane, is a thin, cone-shaped membrane that separates the outer ear canal from the middle ear. When sound waves traveling through the air hit the eardrum, it vibrates. Those vibrations pass to three tiny bones in the middle ear, which amplify the sound and send it to the inner ear. The eardrum also helps protect the middle ear from water, bacteria, and foreign objects. Infections (such as ear infections, or otitis media), rapid pressure changes during flying or diving, or a cotton swab pushed too far can all rupture or perforate the eardrum. Most small perforations heal on their own within a few weeks.

Early satiety means feeling full after eating only a small amount of food — much sooner than you would expect. It can make it difficult to eat a full meal and may lead to unintentional weight loss, malnutrition, and fatigue. Causes include gastroparesis (slowed stomach emptying, often associated with diabetes), gastric outlet obstruction, peptic ulcer disease, GERD, liver disease, or, less commonly, gastric cancer. Early satiety can also be a side effect of certain medications. Persistent early satiety that is limiting your ability to maintain adequate nutrition should be evaluated by a physician with an upper endoscopy or imaging study.

ICD-10: R14

Easy bleeding means bleeding more than expected from minor cuts, dental procedures, or small injuries, or bleeding that is hard to stop. It can also include frequent nosebleeds, prolonged menstrual periods, or blood in urine or stool. Causes include inherited bleeding disorders such as hemophilia or von Willebrand disease, low platelet counts, liver disease, vitamin K deficiency, and certain medications such as blood thinners or aspirin. Easy bleeding should always be reported to a doctor, who will order blood tests including a complete blood count and coagulation studies to identify the cause and guide treatment.

Eating disorders are serious mental health conditions involving persistent disturbances in eating behavior that negatively affect physical health, emotional wellbeing, and daily functioning. Common types include anorexia nervosa (severely restricting food intake), bulimia nervosa (cycles of binge eating and purging), and binge eating disorder (recurring episodes of eating large amounts without purging). These conditions can affect people of any gender, age, or body size. Eating disorders have one of the highest mortality rates of any mental health condition, but they are treatable. Care is typically delivered by a team that may include a therapist, dietitian, physician, and psychiatrist. Early treatment leads to better recovery outcomes.

ICD-10: F50

An echocardiogram is an ultrasound of the heart that creates moving images of your heart's chambers, valves, walls, and blood flow. You will lie on an exam table while a technician places electrodes on your chest and applies gel before moving a transducer over the heart area. The test typically takes 30 to 60 minutes and is painless. A standard transthoracic echo is done on the outside of your chest. A transesophageal echocardiogram involves inserting a probe down the throat and requires sedation. Echo tests show how well your heart pumps blood, detect valve problems, and identify structural abnormalities. No radiation is used. You can usually eat and take medications normally before the test.

Eczema, or atopic dermatitis, is a chronic skin condition characterized by dry, itchy, and inflamed skin. It is very common, especially in children, and often runs in families alongside asthma and allergies. Flare-ups can be triggered by soaps, detergents, sweat, stress, or allergens. While there is no cure, eczema can be managed with moisturizers, topical corticosteroids, prescription non-steroidal creams, and newer biologic medications. Keeping skin well-moisturized and avoiding triggers is key. Most children improve as they grow older, but many adults have ongoing symptoms.

ICD-10: L20

An EEG records the electrical activity of your brain using small metal discs called electrodes attached to your scalp with a sticky paste or a cap. The electrodes detect electrical signals produced by your brain cells and transmit them to a machine that records the patterns as wavy lines. The test is painless and takes 30 to 60 minutes. You may be asked to breathe rapidly, look at a flickering light, or sleep during part of the test to trigger certain brain wave patterns. Wash your hair the night before and avoid products. An EEG is used to diagnose epilepsy, seizure disorders, and other brain conditions. You may be asked to sleep less the night before a sleep-deprived EEG.

An EKG or ECG measures the electrical activity of your heart and records it as a series of waves on paper or a screen. Small sticky electrodes are placed on your chest, arms, and legs. The wires attached to the electrodes detect your heart's electrical signals without sending any electricity into your body. The test is completely painless and takes about 5 to 10 minutes. You will need to lie still and breathe normally. An EKG can detect irregular heart rhythms, evidence of a previous or current heart attack, and other cardiac conditions. It is often done as a routine health screening or before surgery. No special preparation is needed.

Electroconvulsive Therapy (ECT) is a medical procedure in which a brief, controlled electrical current is applied to the brain under general anesthesia to produce a brief seizure. Despite its dramatic-sounding name, ECT is a safe and highly effective treatment for severe depression, bipolar disorder, catatonia, and treatment-resistant mental illness. It is typically given two to three times per week for several weeks. Memory problems are a common but often temporary side effect. ECT is used when medications have failed or when a rapid response is needed, such as in a patient with severe suicidal ideation or inability to eat.

An eligibility condition is a specific requirement—often a diagnosed medical condition—that you must meet before participating in a program or receiving a particular benefit. Examples include a confirmed cancer diagnosis to enroll in a disease management program, a documented permanent disability to qualify for Medicare before age 65, or a specific chronic illness to join a Special Needs Plan. Eligibility conditions are distinct from enrollment deadlines; you may meet the condition at any time but still need to apply during an open window. Providing accurate medical documentation up front speeds up the determination process and reduces the risk of a denial based on missing information.

Eligibility criteria are the formal rules that define who may enroll in or benefit from a health plan, government program, or clinical trial. They may include age ranges, income limits, residency requirements, diagnostic codes, or prior treatment history. Medicaid eligibility criteria vary by state and typically consider household size, income as a percentage of the federal poverty level, citizenship, and disability status. The ACA Marketplace uses income criteria to determine subsidy amounts. Clinical trials list specific inclusion and exclusion criteria in their protocols. Meeting all criteria does not guarantee enrollment if a plan is at capacity or if the enrollment period has closed. Always verify criteria before completing a lengthy application.

An emergency medical condition is an acute illness or injury severe enough that a reasonable person would believe that without immediate treatment, it could seriously jeopardize their health, impair bodily function, or cause serious dysfunction of any organ. This definition, used in EMTALA and insurance regulations, triggers key patient protections: hospitals must screen and stabilize you regardless of insurance status or ability to pay, and your insurer cannot require prior authorization for emergency care. Typical examples include sudden chest pain, difficulty breathing, signs of stroke, severe bleeding, or high fever in an infant. You may still owe cost-sharing after stabilization, but the initial emergency care itself must be covered.

Emergency Medical Services (EMS) refers to the organized system of pre-hospital emergency care provided by trained personnel who respond to 911 calls. EMS includes EMTs, paramedics, and emergency dispatchers. They arrive by ground ambulance or medical helicopter to assess, treat, and transport patients to the appropriate hospital. EMS plays a critical role in stroke, heart attack, trauma, and respiratory emergencies where early treatment improves survival. In the US, call 911 to activate EMS. When you call, stay on the line, tell them the location, what happened, and the patient's condition. Do not drive yourself or an unstable person to the hospital—call 911 instead.

The emergency room (ER), also called the emergency department (ED), is the area of a hospital that treats patients with urgent or life-threatening conditions at any hour of the day or night. You do not need an appointment to be seen. Upon arrival, a nurse will perform a quick triage assessment to determine how quickly you need care. Conditions such as chest pain, stroke symptoms, difficulty breathing, or serious injuries should be treated in the ER. Non-life-threatening issues may be redirected to an urgent care clinic. Wait times vary depending on severity of other patients' conditions.

An EMG records the electrical activity produced by your muscles at rest and during contraction. A thin needle electrode is inserted directly into a muscle to measure its electrical signals. You will be asked to relax and then to contract the muscle gently while the doctor listens to and observes the electrical patterns on a screen. The needle insertions cause brief discomfort similar to a sharp pinch. The test usually takes 30 to 60 minutes. You should keep your skin clean and avoid lotions on the day of the test. EMG is used to diagnose muscle diseases, nerve injuries, and conditions such as ALS or myopathy. It is often done alongside a nerve conduction study.

Emphysema is a chronic lung disease in which the air sacs, called alveoli, are damaged and enlarged, reducing the lung's ability to exchange oxygen. It is a type of COPD and is most often caused by long-term cigarette smoking, though exposure to air pollutants or rare genetic conditions can also cause it. Symptoms include progressive shortness of breath, especially during physical activity, a barrel-shaped chest, and reduced exercise tolerance. Treatment includes bronchodilator inhalers, supplemental oxygen therapy, and pulmonary rehabilitation. In advanced cases, surgical options or lung transplant may be considered. Smoking cessation is the most effective way to slow progression.

ICD-10: J43

Employer-sponsored insurance (ESI) is health coverage provided through a place of employment. Employers typically pay a portion of premiums and employees pay the rest through pre-tax payroll deductions. ESI is the most common source of health insurance in the US, covering about half the population. Employers with 50 or more full-time equivalent employees are required under the ACA to offer coverage meeting minimum value standards. Coverage typically extends to spouses and dependents. Losing employer-sponsored coverage triggers a Special Enrollment Period.

An EMT, or Emergency Medical Technician, is a trained first responder who provides emergency care before and during transport to a hospital. EMTs respond to 911 calls and can perform basic life support such as CPR, controlling bleeding, splinting fractures, and giving oxygen. There are different levels of certification in the US: EMT-Basic and Advanced EMT. EMTs work alongside paramedics, who have more advanced training. When an ambulance arrives, the crew will assess you, begin treatment, and communicate your condition to the hospital before you arrive. You can ask the EMT crew what care they are giving you.

EMTALA, the Emergency Medical Treatment and Labor Act, is a federal law enacted in 1986 requiring Medicare-participating hospitals with emergency departments to provide a medical screening exam to any person who arrives seeking care—regardless of citizenship, ability to pay, or insurance status. If an emergency medical condition is found, the hospital must stabilize the patient or arrange an appropriate transfer. The law also applies to women in active labor. Violations can result in fines up to $50,000 per incident and loss of Medicare funding. EMTALA does not guarantee free care—billing still occurs—but it prevents outright refusal of emergency treatment. Patients who are improperly turned away may file complaints with CMS.

Endocarditis is an infection of the inner lining of the heart's chambers and valves, known as the endocardium. It usually occurs when bacteria or other germs from another part of the body — such as the mouth or skin — spread through the bloodstream and attach to damaged areas of the heart. People with artificial heart valves, congenital heart defects, or a history of endocarditis are at higher risk. Symptoms include fever, chills, fatigue, new or changed heart murmur, and joint pain. Treatment requires prolonged intravenous antibiotic therapy, and sometimes surgery to repair or replace damaged valves.

ICD-10: I33

Endometriosis is a chronic condition in which tissue similar to the lining of the uterus grows outside the uterus, often on the ovaries, fallopian tubes, or pelvic lining. This tissue behaves like the uterine lining — thickening and shedding with each menstrual cycle — but has no way to exit the body, causing inflammation, pain, and scar tissue. Symptoms include severe menstrual cramps, chronic pelvic pain, painful intercourse, and difficulty getting pregnant. It affects an estimated 1 in 10 women of reproductive age. Treatment includes pain medication, hormonal therapy, and surgery.

ICD-10: N80

An upper GI endoscopy is a procedure in which a doctor inserts a thin, flexible tube with a camera through your mouth and down into the esophagus, stomach, and upper small intestine to look for ulcers, inflammation, tumors, or bleeding. You will be given a sedative through an IV so you are relaxed and drowsy, and a numbing spray is applied to your throat. You should not eat or drink for at least six hours beforehand. The procedure typically takes 10 to 20 minutes. Biopsies or treatments can be performed during the same session. You will need someone to drive you home. Mild throat soreness or bloating is common afterward. Full activity resumes the next day.

The epidermis is the outermost layer of your skin — the part you can see and touch. It serves as the body's first barrier against the outside world, protecting you from germs, chemicals, UV radiation, and water loss. The epidermis is constantly renewing itself: old skin cells on the surface shed off every few weeks and are replaced by new cells moving up from below. It also contains melanocytes — cells that produce the pigment melanin, which gives skin its color and helps protect against sun damage. Conditions affecting the epidermis include sunburn, skin infections, and skin cancer. Superficial wounds and first-degree burns affect only this layer.

An epidural is a type of regional anesthesia in which medication is injected into the epidural space of the spine to numb a large area of the body, typically from the waist down. It is commonly used during labor and childbirth, cesarean sections, and lower-body surgeries. A small catheter (thin tube) is usually placed in the epidural space so medication can be given continuously or as needed. The injection is done by an anesthesiologist while the patient sits or lies curled on their side. There is usually mild pressure or a pinch during catheter placement. Side effects may include low blood pressure, headache (rare), or temporary weakness in the legs. The epidural is removed after the procedure and the catheter site heals quickly.

Epilepsy is a neurological disorder characterized by recurrent, unprovoked seizures caused by abnormal electrical activity in the brain. Seizures can vary from brief lapses in awareness to full-body convulsions. They may affect movement, sensation, emotions, or consciousness. Epilepsy can stem from genetics, brain injury, stroke, or infections, and sometimes the cause is unknown. It affects all ages. Seizures can often be controlled with anti-epileptic medications. Surgery, nerve stimulation devices, or specialized diets may help when medications are insufficient. Driving restrictions and safety precautions are important daily considerations.

ICD-10: G40

An epinephrine auto-injector (brand name EpiPen) is a pre-filled, spring-loaded device used to inject epinephrine (adrenaline) into the outer thigh muscle during a severe allergic reaction (anaphylaxis). Anaphylaxis is a life-threatening emergency that can cause throat swelling, difficulty breathing, and a sudden drop in blood pressure. Epinephrine rapidly reverses these symptoms. After using an auto-injector, call 911 or go to the ER immediately, as symptoms may return. People with known severe allergies are prescribed auto-injectors to carry at all times. In hospitals, epinephrine is administered by staff. Inform healthcare providers of all your allergies.

An episode of care refers to all the healthcare services a patient receives for a specific health condition or medical event within a defined period — from the initial encounter through recovery. For example, a knee replacement episode might include the pre-surgery consultation, the surgery itself, hospital stay, physical therapy, and follow-up visits. Insurers and employers increasingly use episode-of-care payments (bundled payments) as a cost-control method. Understanding this concept helps patients know which services are included in a bundled payment arrangement and what falls outside the episode and may be billed separately.

An EPO (Exclusive Provider Organization) combines features of HMO and PPO plans. Like an HMO, it typically does not cover out-of-network care (except emergencies), but like a PPO, it usually does not require referrals to see specialists. Members must use the plan's network of providers for all non-emergency care. EPOs often have premiums between HMO and PPO levels. They are increasingly common in ACA marketplace plans.

The erythrocyte sedimentation rate (ESR) is a blood test that indirectly measures inflammation in your body. When inflammation is present, red blood cells clump together and fall faster to the bottom of a test tube. A lab technician draws blood from a vein in your arm and places it in a tall, thin tube, then measures how many millimeters the cells fall in one hour. A high ESR suggests inflammation but does not pinpoint the cause. Doctors use ESR to screen for inflammatory conditions like rheumatoid arthritis, lupus, temporal arteritis, and infections, and to monitor how well treatment for those conditions is working.

The esophagus is the muscular tube, about ten inches long, that connects your mouth and throat to your stomach. When you swallow, muscles in the esophagus wall contract in a wave-like motion called peristalsis to push food and liquid down to the stomach. At the bottom of the esophagus is a ring of muscle called the lower esophageal sphincter that acts as a valve, opening to let food in and closing to stop stomach acid from coming back up. When this valve is weak, acid reflux or GERD — gastroesophageal reflux disease — occurs. The esophagus sits behind the trachea and in front of the spine in the chest.

In healthcare and benefits contexts, an estate refers to all the property, assets, and outstanding debts a person leaves behind at death. It may include a home, bank accounts, retirement accounts, vehicles, and personal belongings, minus any debts owed. In Medicaid planning, the estate is the primary target for estate recovery, through which state Medicaid agencies seek reimbursement for costs paid during the recipient's lifetime—particularly nursing home and long-term care services received after age 55. Probate is the court-supervised process that settles debts and distributes remaining assets to heirs. Assets held in certain trusts or with named beneficiaries may pass outside probate and thus may be shielded from Medicaid recovery.

Estate recovery is a federal requirement that state Medicaid programs seek reimbursement from a deceased beneficiary's estate for costs of certain services. States must pursue recovery for nursing home and long-term care services provided to Medicaid recipients aged 55 or older; they may also recover costs for other services provided to that age group. Recovery is typically deferred if a surviving spouse, a child under 21, or a blind or disabled child resides in the home. Not all assets pass through probate, so property in certain trusts or with named beneficiaries may be protected. Contact your state Medicaid office early—planning before receiving Medicaid can significantly limit what the state can recover from your family.

The Eustachian tube is a narrow channel that connects the middle ear to the back of the throat and nasal cavity. Its main job is to equalize the air pressure on both sides of the eardrum. When you swallow, yawn, or chew, the tube briefly opens to let air in or out of the middle ear. This is why your ears pop when you change altitude in an airplane or drive up a mountain. The tube also drains any fluid that forms in the middle ear. In children, the Eustachian tube is shorter and more horizontal, making it easier for germs from the throat to reach the middle ear — this is why children get more ear infections than adults. Blocked or dysfunctional Eustachian tubes cause pressure, muffled hearing, and ear pain.

An evidence of coverage (EOC) is a detailed document from your health plan describing all aspects of your coverage for the plan year. It explains covered services, cost-sharing amounts such as deductibles, copays, and coinsurance, network requirements, prior authorization rules, and your rights as a plan member. Medicare Advantage and Part D plans are required to send members a new EOC each year before coverage begins. The EOC is the legally binding contract for your plan—not the shorter summary of benefits. When your insurer denies a claim or prior authorization, the EOC is the primary reference for filing an appeal. Keep your EOC accessible throughout the year.

Excessive daytime sleepiness means feeling very drowsy during the day, beyond what is expected from a normal night's sleep. It can make it hard to stay awake while working, driving, or in social settings. Common causes include obstructive sleep apnea, narcolepsy, shift work, chronic insufficient sleep, sedating medications, depression, and underlying medical conditions. It increases the risk of accidents and impairs concentration and mood. A sleep study may be recommended to identify obstructive sleep apnea or other sleep disorders. Treatment depends on the cause and may include CPAP therapy, lifestyle changes, or medication.

ICD-10: G47

Passing gas is a normal part of digestion; most people pass gas 13 to 21 times per day. Excessive gas, or flatulence, becomes a concern when it is frequent, malodorous, or accompanied by abdominal pain, bloating, or cramping. Gas is produced by bacteria in the large intestine digesting unabsorbed carbohydrates. Common triggers include beans, dairy products in those with lactose intolerance, certain vegetables, artificial sweeteners, and swallowed air. Persistent excessive gas with pain, diarrhea, or weight loss may indicate food intolerance, celiac disease, or inflammatory bowel disease and should be evaluated.

ICD-10: R14

Excessive hunger, or polyphagia, is an abnormally strong and persistent urge to eat, even after consuming a full meal. It is a key symptom of uncontrolled diabetes, where cells cannot absorb glucose properly and the body sends continuous hunger signals. Hyperthyroidism, hypoglycemia, certain medications such as steroids and antihistamines, and psychological conditions such as bulimia nervosa can also cause excessive hunger. When excessive hunger is paired with excessive thirst, frequent urination, and unexplained weight loss despite eating well, diabetes should be strongly suspected and blood glucose should be checked as soon as possible.

ICD-10: R63

Excessive sweating, or hyperhidrosis, means sweating far more than is needed to regulate body temperature. It can affect the entire body or specific areas such as the palms, feet, underarms, or face. Primary hyperhidrosis has no medical cause and often runs in families. Secondary hyperhidrosis results from an underlying condition such as diabetes, thyroid disorders, menopause, anxiety, obesity, or infections. Certain medications can also trigger excessive sweating. Night sweats are a common form and may indicate infection, lymphoma, or hormonal changes. A doctor can identify the cause and recommend treatments ranging from prescription antiperspirants to medications or procedures.

Excessive thirst, medically called polydipsia, means feeling intensely and persistently thirsty even after drinking adequate fluids. It can be a normal response to exercise, hot weather, or a salty meal, but ongoing excessive thirst that doesn't resolve is an important warning sign. It is one of the classic early symptoms of diabetes mellitus, particularly when paired with frequent urination and unexplained fatigue or weight loss. Other causes include diabetes insipidus, certain medications, dry mouth from mouth breathing, and psychogenic polydipsia. New or worsening excessive thirst should always prompt a blood glucose check.

ICD-10: R63

An Excludes 1 note in ICD-10-CM means the excluded condition cannot occur with the code being referenced — these are mutually exclusive conditions. For example, if a code has "Excludes 1: congenital cholera (A00.0)" it means a patient cannot have both the referenced condition and congenital cholera simultaneously. Unlike Excludes 2, you cannot bill both codes on the same claim. The distinction matters for correct claim coding and audit compliance.

An Excludes 2 note in ICD-10-CM means the excluded condition is not included in the referenced code, but both conditions may be present in the same patient simultaneously. When both conditions exist and are documented, both codes may be reported on the same claim. For example, "Excludes 2: influenza (J09-J11)" on a code for upper respiratory infection means a patient could have both, and if documented, both codes should be billed.

An expedited appeal is a fast-track insurance appeals process available when your situation is urgent enough that waiting the standard 30-day review period could seriously jeopardize your health. Both you and your treating physician can request expedited status. Federal law requires insurers to respond within 72 hours of receiving the request. Expedited appeals apply to pre-service decisions, such as a denial of prior authorization for urgent surgery. If the expedited internal appeal is denied, you may immediately request an expedited external review. Always request expedited status in writing, include a statement from your doctor explaining why delay poses a health risk, and document all dates and times of communication with your insurer.

An Explanation of Benefits (EOB) is a document sent by your insurer after a medical claim is processed. It details the services billed, the amount the provider charged, what the insurer paid, any adjustments, and what you owe. An EOB is not a bill — it is a summary of how a claim was handled. Reviewing your EOB helps you catch billing errors, verify that claims were processed correctly, and understand your remaining deductible and out-of-pocket balance.

External review is an independent, binding evaluation of your health insurer's denial by an outside organization not affiliated with the plan. Under the ACA, you have the right to request external review after exhausting your plan's internal appeal process—or immediately in urgent situations. An independent review organization (IRO) staffed by certified medical specialists examines the case without deference to the insurer. If the IRO rules in your favor, the insurer must comply and provide coverage or pay the claim. Federal external review rules apply to most employer plans and Marketplace plans. Grandfathered or self-insured employer plans may follow state or alternative federal processes. External review decisions are final and binding for both parties.

Extra Help, also called the Low Income Subsidy (LIS), is a Social Security Administration program that helps Medicare beneficiaries with limited income and resources pay for Medicare Part D prescription drug costs. Qualifying individuals receive reduced or eliminated premiums, lower deductibles, and capped copayments on covered medications. People who automatically qualify include full Medicaid beneficiaries, those receiving Supplemental Security Income (SSI), and those in a Medicare Savings Program. Others with income below approximately 150% of the federal poverty level may apply directly through Social Security online, by phone, or in person. Enrollment in Extra Help can save beneficiaries hundreds of dollars per month on prescription drug costs throughout the year.

An extraordinary collection action (ECA) is an aggressive debt collection measure that nonprofit hospitals subject to IRS Section 501(r) are prohibited from taking before making a reasonable effort to determine if a patient qualifies for financial assistance. ECAs include reporting medical debt to credit bureaus, filing a lawsuit, obtaining a judgment lien against property, garnishing wages, and seizing bank accounts. Hospitals must give patients at least 120 days from the first billing statement to apply for financial assistance before initiating ECAs. Initiating an ECA prematurely can jeopardize the hospital's tax-exempt status. If you receive a collection notice from a hospital, immediately ask about the financial assistance policy and apply before the deadline.

Eye pain is any discomfort felt in, around, or behind the eye. It may feel like burning, stabbing, aching, or a sensation of something stuck in the eye. Common causes include a scratched cornea, dry eyes, conjunctivitis (pink eye), stye, glaucoma, or eye strain from screen use. Migraines can also cause pain around or behind the eye. Most mild eye pain from irritation or eyestrain resolves with rest and lubricating eye drops. Seek prompt medical attention if eye pain is severe, follows an injury or chemical exposure, causes sudden vision changes, or is accompanied by redness, discharge, or headache.

The facial nerve is the seventh cranial nerve. It controls all of the muscles responsible for facial expression — raising your eyebrows, smiling, closing your eyes, and puffing your cheeks. The facial nerve also carries taste signals from the front two-thirds of the tongue, controls the salivary and tear glands, and provides sensation to part of the ear. Bell's palsy is a common condition in which the facial nerve becomes inflamed, causing sudden weakness or paralysis on one side of the face. This makes the face droop, makes it hard to close one eye, and can cause difficulty speaking or eating. Most people recover fully within a few months. Damage to the facial nerve during ear or parotid gland surgery is a known risk that surgeons work hard to avoid.

Facial pain is discomfort or aching anywhere on the face, including the cheeks, jaw, forehead, or around the eyes. It can feel like a dull ache, sharp shooting pain, burning, or pressure. Common causes include sinus infections (sinusitis), dental problems, temporomandibular joint (TMJ) disorders, trigeminal neuralgia, cluster headaches, shingles, or injury. Referred pain from the neck, ear, or tooth can also cause facial discomfort. Mild facial pain from sinus congestion often responds to decongestants and steam. See a provider if the pain is severe, persistent, follows an injury, or is accompanied by swelling, numbness, fever, or changes in vision.

Failure to thrive (FTT) is a term used when a child is not gaining weight or growing as expected for their age and sex. It is identified on the pediatric growth chart, typically when weight falls below the 3rd to 5th percentile or drops significantly across two major percentile lines. Causes can include not getting enough calories, difficulty absorbing nutrients (as in celiac disease or cystic fibrosis), or underlying medical conditions. A thorough evaluation — including feeding history, blood tests, and sometimes specialist referrals — helps identify the cause. Treatment focuses on the underlying reason and ensuring the child receives enough nutrition.

ICD-10: R62

Fainting (syncope) is a sudden, brief loss of consciousness caused by a temporary drop in blood flow to the brain. You may feel lightheaded, sweaty, or nauseated just before passing out. Common causes include standing up too fast, dehydration, emotional stress, heart rhythm problems, or low blood sugar. Most episodes are harmless and resolve quickly. However, call 911 if someone does not wake up within a minute, if fainting follows chest pain or palpitations, if the person is pregnant, or if episodes recur without a known cause. Place an unconscious person on their side if breathing.

ICD-10: R55

The fallopian tubes are two narrow tubes, one connected to each side of the uterus, that serve as the pathway for eggs released from the ovaries to reach the uterus. When ovulation occurs, the egg travels through the fallopian tube, where it may be fertilized by sperm. If a fertilized egg cannot reach the uterus and implants inside the tube instead, this is called an ectopic pregnancy — a medical emergency. Blocked or scarred fallopian tubes are a common cause of female infertility. Infections, endometriosis, and prior surgeries can damage the tubes. Doctors may use an X-ray dye test (hysterosalpingogram) to check if the tubes are open.

A fasting blood glucose test measures the amount of sugar (glucose) in your blood after you have not eaten for at least eight hours. Glucose provides energy to every cell, but chronically high levels damage blood vessels and nerves. A nurse or technician draws blood from a vein in your arm or uses a finger-prick. A normal result is below 100 mg/dL. A result between 100–125 mg/dL suggests prediabetes, and 126 mg/dL or higher on two separate occasions indicates diabetes. Doctors use this test for routine screening, diabetes diagnosis, and to check how well dietary or medication changes are working.

Fatigue is a persistent feeling of tiredness or lack of energy that is not relieved by rest. It differs from normal sleepiness and can interfere with daily activities. Common causes include anemia, thyroid disorders, diabetes, depression, sleep problems, chronic infections, and cancer. Certain medications can also cause fatigue. You should see a doctor if fatigue is severe, lasts more than two weeks, or is accompanied by other symptoms such as unexplained weight loss, fever, or shortness of breath, as it may signal an underlying medical condition requiring evaluation.

ICD-10: R53

Fatty liver disease occurs when too much fat builds up in the liver cells. There are two main types: alcoholic fatty liver disease, caused by heavy alcohol use, and non-alcoholic fatty liver disease (NAFLD), which is not related to alcohol. NAFLD is strongly linked to obesity, type 2 diabetes, high triglycerides, and metabolic syndrome. In many people it causes no symptoms, though some experience fatigue and upper right abdominal discomfort. If inflammation develops alongside fat buildup, the condition is called NASH (non-alcoholic steatohepatitis), which can progress to cirrhosis and liver failure. Treatment focuses on weight loss, healthy diet, exercise, and controlling blood sugar and cholesterol levels.

ICD-10: K76

The Fair Debt Collection Practices Act (FDCPA) is a federal law that restricts what third-party debt collectors can say and do when pursuing debts, including medical bills. Collectors cannot call before 8 a.m. or after 9 p.m., use abusive language, make false statements about the debt, or report inaccurate information to credit bureaus. Within 30 days of first contact, you can send a written debt validation letter demanding proof that the debt is valid and that the collector has the legal right to collect it. You can also send a cease-communication letter to stop further contact. Collectors who violate the FDCPA may be sued for up to $1,000 in statutory damages plus attorney fees. Note that original creditors—such as the hospital itself—are generally not covered by the FDCPA.

A febrile seizure is a convulsion in a young child triggered by a rapid rise in body temperature (fever), most commonly between ages 6 months and 5 years. The child's body may shake or jerk uncontrollably for 1 to 3 minutes. Although terrifying to witness, simple febrile seizures are generally harmless and do not cause brain damage or epilepsy. Do not restrain the child; lay them on their side, clear the area, and time the seizure. Call 911 if it lasts more than 5 minutes. Take your child to the doctor after the episode to find the cause of the fever.

ICD-10: R56

The federal poverty level (FPL) is an income measure published annually by the U.S. Department of Health and Human Services that is used as the basis for determining eligibility for dozens of federal health and social programs. For health coverage, it sets the threshold for Medicaid eligibility (typically up to 138% FPL in expansion states), Children's Health Insurance Program (CHIP), premium tax credits on the ACA Marketplace (100%–400% FPL for most households), and Extra Help for Medicare Part D. The FPL scales with household size, so a larger family can have a higher income and still qualify. Alaska and Hawaii use higher FPL figures to account for cost-of-living differences. Changes in income or family size during the year can affect your eligibility.

A federally qualified health center (FQHC) is a community health clinic that meets federal requirements and receives grant funding from the Health Resources and Services Administration (HRSA) under Section 330 of the Public Health Service Act. FQHCs must offer comprehensive primary care services—including medical, dental, behavioral health, and substance use treatment—to all patients in their area, regardless of ability to pay. Charges are calculated on a sliding-scale fee based on income and family size, so patients pay only what they can afford. FQHCs receive enhanced Medicare and Medicaid reimbursement rates. With over 1,400 grantees operating more than 14,000 service sites nationwide, FQHCs are a vital resource for uninsured and underserved communities.

A fee schedule is a complete list of maximum reimbursement amounts that an insurance plan or government program (like Medicare) will pay for each specific medical service, identified by procedure code. Providers who participate in a network agree to accept these scheduled rates as payment in full (minus your cost-sharing). The Medicare Physician Fee Schedule (MPFS) is a widely referenced public standard. Private insurers negotiate their own fee schedules with providers. For patients, the fee schedule effectively sets the allowed amount for each service. Knowing fee schedules can help you estimate your out-of-pocket costs before receiving care.

The femur is your thigh bone — the longest and strongest bone in the human body. It runs from your hip down to your knee. At the top, a rounded ball fits into the hip socket to form the hip joint. At the bottom, it connects with the tibia and kneecap to form the knee. The femur supports your full body weight when you stand and walk. Inside, it contains bone marrow that produces blood cells. A femur fracture is a serious injury often requiring surgery. Your doctor may order an X-ray, CT scan, or MRI to evaluate this bone.

FERPA, the Family Educational Rights and Privacy Act, protects the privacy of student education records at schools that receive federal funding. It becomes relevant in healthcare when student health services are documented as part of school records—for example, visits to a school nurse, an IEP containing medical information, or participation in a school-based health program. HIPAA generally does not apply to school health records covered by FERPA. Parents control FERPA rights for students under 18; at 18 or upon college enrollment, rights transfer to the student. When requesting school health records, the process differs from a standard HIPAA records request. Schools may not disclose records without written consent except in limited circumstances.

Ferritin is a protein that stores iron inside your cells and releases it when your body needs it. A ferritin blood test measures how much stored iron you have. Low ferritin is one of the earliest signs of iron deficiency, often appearing before anemia develops. High ferritin can result from iron overload disorders (like hemochromatosis), chronic inflammation, liver disease, or certain cancers, since ferritin also acts as an acute-phase protein. Blood is drawn from a vein in your arm. Fasting is not generally required. Doctors use the ferritin level alongside other iron-studies results to diagnose the cause of fatigue, anemia, or suspected iron overload.

Fetal monitoring tracks your baby's heart rate during pregnancy or labor to check for signs of distress. Two main types are used in labor: external monitoring, which uses sensors strapped to your abdomen, and internal monitoring, which uses a small electrode attached to the baby's scalp. Before labor, a non-stress test (NST) or biophysical profile (BPP) may be ordered to check that the baby is doing well. The baby's heart rate normally speeds up with movement. Decelerations or unusual patterns can signal that the baby needs more oxygen, prompting a faster delivery. Fetal monitoring is standard during labor and delivery in US hospitals.

ICD-10: Z36

Fever is a rise in body temperature above 100.4°F (38°C). It is usually a sign that your immune system is fighting an infection, such as the flu, a cold, or a bacterial illness. Other causes include inflammation, certain medications, or heat exposure. Mild fevers often resolve with rest and fluids. Seek care if your temperature exceeds 103°F, if the fever lasts more than three days, or if it is accompanied by severe headache, rash, stiff neck, or difficulty breathing. Infants under three months with any fever need immediate medical attention.

ICD-10: R50

Fibromyalgia is a chronic condition characterized by widespread musculoskeletal pain, fatigue, sleep problems, and cognitive difficulties often called "fibro fog." The nervous system amplifies pain signals, making normal sensations feel intensely painful. Tender points throughout the body are common. It often coexists with headaches, irritable bowel syndrome, and depression. Triggers can include physical or emotional trauma, infections, or stress. There is no cure, but treatment with medications, exercise, stress management, and cognitive behavioral therapy can significantly reduce symptoms and improve quality of life.

ICD-10: M79

The fibula is the thinner bone on the outer side of your lower leg, running alongside the tibia from the knee to the ankle. Although it is not a major weight-bearing bone, it plays an important role in stabilizing the ankle joint and providing attachment points for several muscles. The fibula forms the outer part of the ankle where it touches the ankle bone. Fibula fractures often occur from twisting injuries or direct impacts. A common injury is a lateral malleolus fracture, which affects the bony bump on the outside of your ankle. Treatment depends on fracture severity and can include immobilization or surgery.

A financial assistance policy (FAP), sometimes called a charity care policy, is a written document that nonprofit hospitals are required to maintain under IRS Section 501(r) to keep their tax-exempt status. The FAP must describe who qualifies for free or discounted care, how to apply, what documentation is required, and how the hospital calculates discounted charges. Hospitals must widely publicize the FAP—posting it on their website, making paper copies available on request, and mentioning it in billing statements. ACA rules require that patients with income up to at least 200% of the federal poverty level receive some financial assistance. Always ask for a FAP application as soon as you receive care at a nonprofit hospital, even if you were not offered one.

Flank pain is discomfort felt on one or both sides of the body, between the lower ribs and the hip. It can range from a mild, dull ache to severe, cramping pain. The most common causes are kidney stones, urinary tract infections (UTIs), kidney infections (pyelonephritis), or musculoskeletal problems such as a muscle strain. Kidney stone pain often comes in intense waves and may radiate to the groin or inner thigh. Flank pain from a kidney infection is usually accompanied by fever, chills, and painful urination. See a provider promptly if you have fever, blood in your urine, severe or worsening pain, vomiting, or any difficulty urinating.

Fluoroscopy is a real-time X-ray technique that produces continuous moving images of the inside of your body, similar to an X-ray movie. A contrast dye is often swallowed, injected into a joint, or administered through a catheter to make structures visible. The images appear on a monitor and allow the doctor to observe the movement of organs, blood vessels, or instruments during procedures such as catheter placement, barium swallow studies, or joint injections. You may need to fast beforehand depending on what is being examined. Radiation exposure is higher than a regular X-ray because the beam is continuous. Your radiology team uses protective shielding to minimize exposure. The procedure length varies widely by type.

Flushing is sudden redness of the face, neck, or chest, often accompanied by a feeling of warmth. It commonly results from emotional reactions, hot drinks, spicy foods, alcohol, or physical exertion. Medical causes include menopause hot flashes, rosacea, carcinoid syndrome, mastocytosis, medication side effects, and certain hormonal tumors. Flushing that occurs repeatedly without an obvious trigger, or is associated with diarrhea, wheezing, or palpitations, should be investigated by a doctor. Blood and urine tests can help identify hormone-producing tumors or other conditions responsible for recurrent, unexplained flushing episodes.

The Federal Medical Assistance Percentage (FMAP) is the share of each state's Medicaid expenditures paid by the federal government. It is calculated annually using each state's average per-capita income relative to the national average—poorer states receive a higher federal match and thus more funding. FMAP rates range from 50% in higher-income states such as Connecticut to over 75% in lower-income states such as Mississippi. Congress may temporarily increase the FMAP during public health emergencies or economic downturns to help states maintain coverage. An enhanced FMAP rate of 90% applies to ACA Medicaid expansion populations, meaning the federal government covers 90 cents of every dollar spent on those enrollees, leaving states to cover only 10%.

Form 1095-A is the Health Insurance Marketplace Statement sent each January by your federal or state Marketplace if you were enrolled in a Marketplace plan during the previous year. The form shows the months you and your household members had coverage, the premium for the second-lowest-cost silver plan (SLCSP) in your area—used as the benchmark for calculating the premium tax credit—and the amount of any advance premium tax credit (APTC) paid on your behalf during the year. You must use Form 1095-A to complete Form 8962 and reconcile your actual premium tax credit on your federal tax return. Contact your Marketplace immediately if the form is not received by mid-January or contains errors.

Form 8962 is the IRS tax form used to calculate and reconcile the Premium Tax Credit (PTC) for people who enrolled in an ACA Marketplace health plan. If you received advance premium tax credits during the year to reduce your monthly premiums, you must file Form 8962 with your federal tax return to reconcile those payments against the credit you are actually entitled to based on your final household income. If you received too much in advance credits, you must repay the difference (subject to caps for lower incomes); if too little, you receive the remainder as a refund or a reduction in taxes owed. Form 8962 cannot be completed without Form 1095-A. Failing to file when required can block you from receiving advance premium tax credits in future plan years.

Form SSA-44 is a Social Security Administration document you complete to ask Medicare to lower your Income-Related Monthly Adjustment Amount (IRMAA) because of a life-changing event—such as retirement, divorce, or the death of a spouse—that significantly reduced your income since the tax year Medicare used to set your current premium. You submit the form with supporting evidence such as a retirement letter or amended tax return. If approved, Medicare recalculates your Part B and Part D premiums using a more recent, lower income year. Without filing this form, you would wait until your tax data naturally updates in the Social Security system, which can take two or more years.

A formulary exception is a formal request you or your doctor sends to your health insurance plan asking it to cover a prescription drug not on the plan's approved drug list, or to cover it at a lower cost-sharing tier. You typically need a letter of medical necessity explaining why a covered alternative would not work for your specific condition. Insurance plans must decide standard exception requests within 72 hours and urgent requests within 24 hours. If the request is denied, you can file an internal appeal. Medicare Part D and most ACA marketplace plans have a formulary exception process. Ask your doctor to submit the request on your behalf to improve approval chances.

A formulary tier is your health insurance plan's way of grouping covered drugs by how much you pay out of pocket. Most plans have three to five tiers, with Tier 1 covering the least expensive preferred generic drugs and higher tiers covering brand-name or specialty drugs that cost more. The tier determines your copay or coinsurance for each fill. If your medication falls on a high tier, you can ask your doctor about lower-tier alternatives or request a formulary exception from your insurance plan if no alternative is appropriate. Checking the formulary before starting a new prescription can prevent unexpected costs at the pharmacy.

A Federally Qualified Health Center (FQHC) is a community-based health clinic that receives federal grant funding under Section 330 of the Public Health Service Act. FQHCs must provide comprehensive primary care services to all patients regardless of insurance status or ability to pay, using a sliding fee scale. They serve medically underserved areas and populations and must meet federal performance standards. Services include primary care, mental health, dental, and pharmacy. FQHCs receive enhanced Medicare and Medicaid reimbursement rates.

Frequent urination means needing to urinate more often than usual — typically more than eight times in a 24-hour period. It can disrupt sleep if it occurs at night, a condition called nocturia. Common causes include drinking large amounts of fluids, urinary tract infections, diabetes mellitus or insipidus, overactive bladder, prostate enlargement in men, pregnancy, and diuretic medications. Frequent urination accompanied by excessive thirst, burning, blood in the urine, or pain should be evaluated by a healthcare provider. In diabetic patients, frequent urination is one of the first signs that blood sugar is poorly controlled.

ICD-10: R35

The frontal lobe is the front portion of your brain, located just behind your forehead. It is the largest of the brain's four lobes and handles many of the abilities that make us uniquely human. It controls voluntary movement, planning, decision-making, problem-solving, and personality. The frontal lobe also manages impulse control and social behavior. A strip at the back of the frontal lobe called the motor cortex sends signals to move muscles throughout your body. Strokes, tumors, or injuries affecting the frontal lobe can change personality, cause difficulty speaking (called Broca's aphasia), or weaken movement on one side of the body. It is often referenced in neurology and brain surgery notes.

A Flexible Spending Account (FSA) is an employer-sponsored pre-tax benefit account used to pay for eligible medical, dental, and vision expenses. Contributions reduce your taxable income. Unlike HSAs, FSAs generally follow a 'use it or lose it' rule — unspent funds may be forfeited at year-end, though some plans allow a grace period or limited rollover. FSAs can be used with any health plan type, not just HDHPs. Annual contribution limits are set by the IRS.

An FSA-eligible expense is a medical, dental, or vision cost that qualifies for payment using Flexible Spending Account funds. The IRS determines which expenses qualify. Eligible items include deductibles, copays, coinsurance, prescription medications, eyeglasses and contact lenses, dental work, medical equipment, and many over-the-counter medicines (without a prescription, thanks to the CARES Act). Non-eligible expenses include cosmetic procedures, gym memberships, and non-medical items. The FSA administrator or IRS Publication 502 provides the complete list.

The full premium is the total monthly cost of a health insurance plan before any employer contribution, government tax credit, or cost-sharing reduction is applied. When you have employer-sponsored insurance, your employer typically pays a large portion and you pay the rest through payroll deduction. If you lose your job and elect COBRA continuation coverage, you must pay the full premium—your share plus the employer share—plus a 2 percent administrative fee. Knowing the full premium helps you compare the true cost of COBRA against ACA marketplace plans that may qualify for Advance Premium Tax Credits, which can make marketplace options significantly cheaper.

The gallbladder is a small, pear-shaped organ about four inches long that sits beneath the liver in the upper right abdomen. Its job is to store and concentrate bile — a yellowish-green digestive fluid made by the liver — and release it into the small intestine after a meal to help digest fats. Gallstones are the most common gallbladder problem. They form when bile hardens into stone-like pieces inside the gallbladder, which can cause severe pain in the upper right abdomen — called biliary colic — especially after eating fatty foods. If a gallstone blocks the bile duct it can cause jaundice — yellowing of the skin. The gallbladder can be removed surgically — a cholecystectomy — and people live normally without it.

Gallstones are hardened deposits that form in the gallbladder, a small organ beneath the liver that stores bile. Bile is a digestive fluid that helps break down fats. Gallstones form when bile contains too much cholesterol, too much bilirubin, or insufficient bile salts. Many gallstones cause no symptoms. However, when a stone blocks a bile duct, it triggers sudden and intense pain in the upper right abdomen (called biliary colic), often following a fatty meal. Complications include gallbladder infection and inflammation. Risk factors include obesity, female sex, pregnancy, rapid weight loss, and high-fat diet. Treatment for symptomatic gallstones is usually surgical removal of the gallbladder.

ICD-10: K80

Gastric bypass is a bariatric surgery that creates a small pouch from the stomach and connects it directly to the small intestine, bypassing most of the stomach and the upper small intestine. This reduces the amount of food the body can hold and absorb, leading to significant weight loss. It is typically recommended for people with severe obesity whose health has not improved with diet and exercise. Surgery is done under general anesthesia and takes two to three hours. Hospital stay is two to three days. Long-term lifestyle changes including diet modifications and vitamin supplements are required afterward. Most patients lose 60 to 80 percent of their excess body weight over one to two years.

General anesthesia is a medically induced state of complete unconsciousness used during surgery or major procedures so the patient feels no pain and has no awareness or memory of the operation. It is administered through intravenous medication and gases inhaled through a breathing tube or mask. The anesthesiologist monitors breathing, heart rate, blood pressure, and oxygen levels throughout the procedure. You will need to fast for several hours before surgery to prevent vomiting during anesthesia. After surgery, you will wake up in a recovery area and may feel groggy, nauseated, or confused for a short time. Most side effects resolve within hours. You should arrange for someone to drive you home as you cannot drive the day of your procedure.

The General Enrollment Period (GEP) runs from January 1 through March 31 each year and allows you to sign up for Medicare Part A or Part B if you missed your Initial Enrollment Period and do not qualify for a Special Enrollment Period. Coverage typically begins July 1 of the same year. If you delayed enrollment without having creditable employer coverage, you may face a permanent late-enrollment penalty added to your monthly premium for each full 12-month period you were eligible but did not enroll. Individuals who had active employer coverage and lost it can usually enroll penalty-free within eight months using a Special Enrollment Period instead.

Generalized anxiety disorder (GAD) is a condition in which a person feels excessive, hard-to-control worry about many different areas of life — such as health, work, finances, family, or everyday tasks — most days for at least six months. The worry is often disproportionate to actual circumstances and interferes with daily functioning. Physical symptoms can include muscle tension, headaches, fatigue, difficulty sleeping, irritability, and an unsettled stomach. GAD is one of the most common anxiety disorders in the US. Treatment is effective and typically includes therapy — especially cognitive behavioral therapy — relaxation techniques, and sometimes medication. Your primary care provider can help initiate treatment or refer you to a mental health specialist.

ICD-10: F41

A generic drug is a medication that contains the same active ingredient, dosage form, strength, and route of administration as a brand-name drug, but is marketed under its chemical name after the brand's patent expires. Generic drugs are approved by the FDA and are therapeutically equivalent to their brand-name counterparts. They are significantly cheaper — often 80–85% less costly — and are placed in the lowest-cost formulary tiers. Requesting generics from your prescriber and pharmacist is a key way to reduce medication costs.

Genetic testing analyzes your DNA to identify changes or mutations in genes, chromosomes, or proteins that may indicate a risk for certain inherited diseases or conditions. Samples are usually collected through a blood draw, cheek swab, or saliva sample. Results may take days to several weeks depending on the complexity of the analysis. Genetic tests are used for many purposes, including diagnosing hereditary conditions, assessing cancer risk such as BRCA gene mutations, determining medication responses, or evaluating prenatal health. A genetic counselor may meet with you before and after testing to explain what the results mean for you and your family. Results can have important implications for relatives, so counseling is strongly recommended.

GERD, or gastroesophageal reflux disease, is a chronic digestive condition where stomach acid frequently flows back into the esophagus, irritating its lining. This happens when the muscle between the esophagus and stomach, the lower esophageal sphincter, does not close properly. Symptoms include heartburn, a burning sensation in the chest, regurgitation of food or sour liquid, difficulty swallowing, and chronic cough. Lifestyle changes such as losing weight, avoiding trigger foods, eating smaller meals, and not lying down after eating can help. Medications including antacids and proton pump inhibitors reduce stomach acid. Severe or persistent GERD may require endoscopy or surgical treatment.

ICD-10: K21

Gestational age is how far along your pregnancy is, measured in weeks starting from the first day of your last menstrual period — not from conception. A full-term pregnancy is 39 to 40 weeks. Providers use gestational age to track your baby's development, schedule appropriate tests, and assess whether labor is early or on time. An early ultrasound can confirm or adjust the gestational age if it differs from calendar counting. Knowing your gestational age also determines whether your baby would be considered premature, full-term, or post-term if born at that point.

ICD-10: Z34

Gestational diabetes is high blood sugar that develops during pregnancy in people who did not have diabetes before. Hormones from the placenta can block insulin, making it harder for your body to manage glucose. It is usually detected by a glucose screening test between weeks 24 and 28. If untreated, it can cause your baby to grow larger than normal, increasing the risk of a difficult delivery and low blood sugar in the newborn. Management includes monitoring blood sugar, dietary changes, and sometimes insulin. Gestational diabetes typically resolves after delivery, but increases your long-term risk of type 2 diabetes.

ICD-10: O24

Glaucoma is a group of eye diseases that damage the optic nerve, usually due to elevated pressure inside the eye. It is a leading cause of blindness in the US. Glaucoma often has no symptoms in the early stages, making regular eye exams essential. As it progresses, patients may notice loss of peripheral (side) vision. Risk factors include high eye pressure, age over 60, family history, and certain medical conditions. Treatment cannot reverse damage already done but can slow progression. Options include eye drops, laser treatment, and surgery.

ICD-10: H40

The global period is the specific number of days around a surgery during which routine follow-up care by the operating surgeon is considered part of the original surgical fee and not billed separately. CMS defines global periods as 0 days, 10 days, or 90 days depending on the procedure. During the global period, the surgeon is expected to provide follow-up visits included in the surgical payment. If you see a new, unrelated problem during the global period, or require unexpected additional care, a separate charge may apply. Knowing your procedure's global period helps you understand which post-surgery visits should have no extra charge.

A glucose tolerance test measures how your body processes sugar and is used to diagnose diabetes or gestational diabetes. You will fast for eight to twelve hours before the test. A fasting blood sample is drawn, and then you drink a sweet glucose solution. Blood samples are collected one, two, or sometimes three hours later to see how your blood sugar levels change over time. You should remain seated and avoid eating, drinking, or smoking during the waiting period. The waiting time can be two to three hours total, so bring something quiet to do. During pregnancy, a one-hour screening test is usually done first, followed by the three-hour GTT if results are elevated. You may feel nausea from the sweet drink.

A Good Faith Estimate (GFE) is a written cost estimate that healthcare providers are required to give uninsured or self-pay patients before a scheduled service costing at least $400. The estimate must list expected charges for the primary service and related items—such as labs, anesthesia, or facility fees—reasonably expected at the same time. Under the No Surprises Act, if your final bill exceeds the Good Faith Estimate by more than $400, you have the right to dispute the charge through the patient-provider dispute resolution process. Always request a GFE before any planned procedure to budget your out-of-pocket costs and identify unexpected add-ons in advance.

Gout is a form of inflammatory arthritis caused by a buildup of uric acid crystals in the joints. Uric acid is a waste product formed when the body breaks down purines, substances found in certain foods and drinks such as red meat, shellfish, and alcohol. When uric acid levels become too high, needle-like crystals form in joints, triggering sudden episodes of intense pain, swelling, redness, and warmth, most commonly in the big toe. Attacks can last days to weeks. Without treatment, repeated episodes can cause permanent joint damage. Treatment includes anti-inflammatory medications during attacks and long-term medications to lower uric acid levels.

ICD-10: M10

A grace period is a set amount of time after your health insurance premium payment due date during which your coverage remains active even if you have not yet paid. For ACA Marketplace plans receiving a premium tax credit, the grace period is 90 days; for plans without subsidies, it is typically 30 days. During the grace period your coverage is technically at risk — providers may not be paid, and the insurer may hold claims until payment is made. If you do not pay by the end of the grace period, your coverage can be canceled retroactively, and you may owe the provider for any claims incurred during that period.

Grief counseling is a form of therapy that supports people who are coping with loss — the death of a loved one, the end of a relationship, a serious illness, or another significant life change. Grief is a natural human response to loss, but for some people it becomes prolonged or complicated and significantly impairs daily functioning. A grief counselor or therapist helps you process your feelings, develop healthy coping strategies, and find meaning after loss without rushing or minimizing your pain. Grief counseling may be covered by insurance when it is delivered by a licensed therapist or clinical social worker. Many hospice and hospital programs also offer free or low-cost grief support groups.

A grievance is a formal complaint you file with your health insurance plan about a non-coverage issue—such as poor customer service, difficulty scheduling appointments, long wait times, or problems getting prescription refills. Grievances differ from appeals, which challenge coverage denials. Medicare Advantage and Part D plans must acknowledge urgent grievances within 24 hours and resolve standard ones within 30 days. Most marketplace and employer plans follow similar timelines. If the plan's response does not resolve your concern, you can escalate to your state insurance commissioner or to the federal Centers for Medicare and Medicaid Services. Keep written records of all grievances and responses.

A ground ambulance is a land vehicle staffed by emergency medical technicians or paramedics that transports patients to a hospital during a medical emergency. Medicare Part B covers ground ambulance transport when other transportation would endanger your health, typically to the nearest appropriate facility. Some ambulance providers are out-of-network, which can lead to surprise bills. Federal protections under the No Surprises Act now limit surprise ground-ambulance billing in many situations, though separate federal rules continue to be developed. Verify whether your ambulance provider participates in your insurance network when possible. If you receive an unexpected bill, contact your insurer and request a cost review.

A group health plan is health insurance offered by an employer or another organization — such as a union — to its employees or members and their eligible dependents. Group plans spread the financial risk across all enrolled members, typically making premiums lower than individual market plans. Employers usually pay a portion of the premium, and employees pay the remainder through payroll deductions. Group health plans are governed by federal laws including ERISA and the ACA. If you lose your job, you may be able to continue group coverage temporarily through COBRA. Enrollment is usually limited to specific open enrollment or qualifying life events.

Guillain-Barré syndrome (GBS) is a rare autoimmune disorder in which the immune system attacks the peripheral nervous system, causing rapidly progressive muscle weakness that typically starts in the feet and legs and moves upward. In severe cases it can cause paralysis and breathing difficulties requiring hospitalization. It is often triggered by a respiratory or gastrointestinal infection. Most people improve significantly, but recovery can take weeks to years. Treatment in hospital includes intravenous immunoglobulin (IVIG) or plasma exchange, followed by intensive rehabilitation to regain muscle strength and function.

ICD-10: G61

Hair loss, also called alopecia, refers to losing more hair than usual from the scalp or other parts of the body. Some hair shedding is normal, but excessive loss can be distressing. Common causes include hereditary pattern baldness, hormonal changes such as pregnancy or menopause, thyroid disorders, iron deficiency anemia, autoimmune conditions such as alopecia areata, and certain medications including chemotherapy agents. Stress and poor nutrition can also contribute. See a doctor if you notice rapid hair thinning, bald patches, or hair loss across the scalp, so the underlying cause can be identified and treated.

ICD-10: L65

Hallucinations are sensory experiences that feel real but are created by the mind rather than external reality. They can involve seeing things, hearing voices or sounds, smelling odors, or feeling sensations that others do not perceive. Causes include psychotic disorders such as schizophrenia, severe depression, bipolar disorder, dementia, delirium, high fever, substance intoxication or withdrawal, brain tumors, and certain medications. Hallucinations are always significant and require medical evaluation. New or worsening hallucinations, especially combined with confusion or unusual behavior, should be assessed urgently, as they may indicate a serious psychiatric or neurological emergency.

Hand, foot, and mouth disease (HFMD) is a common viral illness caused by enteroviruses, most often Coxsackievirus A16. It mainly affects children under 5. Symptoms include fever, mouth sores (making eating painful), and a blister-like rash on the palms, soles, and sometimes the buttocks. It spreads easily through saliva, blister fluid, and stool. Most children recover fully within 7 to 10 days without treatment. Offer soft, cool foods and fluids to prevent dehydration. There is no vaccine in the US. Children should stay home from daycare until fever is gone and blisters have crusted over.

ICD-10: B08

The Healthcare Common Procedure Coding System (HCPCS, pronounced "hick-picks") is a set of codes used to bill Medicare, Medicaid, and other US health plans. Level I consists of CPT codes (for physician procedures); Level II consists of alphanumeric codes (A0000–V9999) for ambulance services, durable medical equipment, drugs, prosthetics, and other items not covered by CPT. Insurers use HCPCS codes to determine coverage and payment.

A High-Deductible Health Plan (HDHP) has higher deductibles and lower premiums than traditional plans. The IRS sets minimum deductible thresholds annually that a plan must meet to qualify as an HDHP. The main benefit of an HDHP is eligibility to open a Health Savings Account (HSA), allowing pre-tax savings for medical expenses. HDHPs make sense for healthy individuals who rarely use healthcare and want to build HSA savings for future or retirement medical costs.

A headache is pain or discomfort in the head, scalp, or neck. Headaches can feel like throbbing, pressing, or squeezing and range from mild to severe. Common types include tension headaches, migraines, and cluster headaches. Triggers include stress, dehydration, poor sleep, eyestrain, or infections such as a cold or flu. Most headaches respond to rest, fluids, and over-the-counter pain medicines. Seek immediate care if your headache is sudden and extremely severe, follows a head injury, or comes with fever, stiff neck, confusion, vision changes, or weakness, as these can signal a serious condition.

ICD-10: R51

The Health Insurance Marketplace (also called the Exchange) is a platform created by the ACA where individuals and families can compare and purchase ACA-compliant health insurance plans. Plans are organized into metal tiers (Bronze, Silver, Gold, Platinum) based on actuarial value. Eligible enrollees may receive Advanced Premium Tax Credits and Cost-Sharing Reductions to lower their costs. The federal marketplace is accessible at HealthCare.gov; some states operate their own exchanges.

A Health Professional Shortage Area (HPSA) is a location, population group, or facility designated by the federal government as lacking enough primary care, dental, or mental health providers relative to the local population. Patients in HPSAs often face long travel distances, extended wait times, or no specialist access. Federally Qualified Health Centers and Rural Health Clinics frequently serve HPSA communities. Being in a HPSA may qualify you for telehealth waivers, expanded Medicaid benefits, or sliding-fee clinic discounts. Clinicians practicing in HPSAs may earn National Health Service Corps loan repayment. You can look up HPSA designation status through the HRSA Data Warehouse website.

A Health Reimbursement Arrangement (HRA) is an employer-funded account that reimburses employees for qualified medical expenses and sometimes health insurance premiums. Unlike an HSA, only employers contribute to an HRA — employees cannot add their own money. The employer sets the annual contribution limit. Common HRA types include the Individual Coverage HRA (ICHRA) and Qualified Small Employer HRA (QSEHRA). HRA funds are generally tax-free and do not roll over in all arrangements. Unused funds stay with the employer if you leave. HRAs can supplement or sometimes replace traditional group health insurance depending on the plan type.

A Health Savings Account (HSA) is a tax-advantaged bank account available to people enrolled in a qualifying High-Deductible Health Plan (HDHP). You, your employer, or both can contribute pre-tax dollars up to the IRS annual limit. Funds pay for qualified medical expenses—doctor visits, prescriptions, dental, vision—without federal income tax. Unlike a Flexible Spending Account, unused HSA money rolls over indefinitely and can earn interest or investment returns. After age 65, you can withdraw HSA funds for any reason without penalty, though non-medical withdrawals are taxed like traditional retirement account distributions. An HSA is one of the only triple-tax-advantaged accounts under federal law.

Hearing loss means a partial or complete inability to hear sounds in one or both ears. Gradual hearing loss is often due to aging (presbycusis), chronic noise exposure, or earwax buildup. Sudden hearing loss — losing hearing over hours to days — can result from inner ear inflammation, viral infection, or vascular problems and is a medical emergency requiring prompt treatment, ideally within 24 to 72 hours. See a doctor immediately if hearing loss is sudden, affects only one ear, or is accompanied by ear pain, drainage, dizziness, or ringing. Treatment with steroids is most effective when started early, making rapid evaluation critical.

ICD-10: H91

A heart attack, medically called a myocardial infarction, occurs when blood flow to a part of the heart muscle is blocked, causing that tissue to begin dying. The blockage is usually caused by a blood clot that forms at the site of plaque buildup in a coronary artery. Symptoms include chest pain or pressure, pain radiating to the arm or jaw, shortness of breath, sweating, and nausea. A heart attack is a medical emergency. Call 911 immediately. Fast treatment such as clot-dissolving drugs or stenting can restore blood flow and minimize permanent heart damage.

ICD-10: I21

Heart failure means the heart cannot pump enough blood to meet the body's needs. Despite the name, it does not mean the heart has stopped; rather, it is not working as efficiently as it should. This causes fluid to back up in the lungs, legs, and other tissues. Symptoms include shortness of breath, swelling in the legs and ankles, fatigue, and difficulty lying flat to sleep. Heart failure is usually caused by coronary artery disease, high blood pressure, or a previous heart attack. Treatment includes medications, lifestyle changes, monitoring daily weight, and in some cases implantable devices or surgery.

ICD-10: I50

Heart palpitations are sensations that your heart is beating hard, fast, fluttering, or skipping a beat. They may be felt in the chest, throat, or neck. Palpitations are often caused by caffeine, alcohol, stress, anxiety, dehydration, or lack of sleep. Less commonly they signal heart rhythm disorders (arrhythmias), thyroid disease, anemia, or heart valve problems. Most palpitations are harmless and brief. Call 911 if palpitations occur with chest pain, shortness of breath, fainting, severe dizziness, or if you have a known heart condition. Keep a log of when they occur — frequency, duration, and associated symptoms — and share it with your doctor.

ICD-10: R00

Heartburn is a burning discomfort in the chest, usually felt behind the breastbone, that often rises toward the throat. Despite its name, it has nothing to do with the heart. It occurs when stomach acid flows back up into the esophagus, the tube connecting the mouth and stomach. Heartburn is very common and is often triggered by fatty or spicy foods, citrus, tomatoes, alcohol, caffeine, eating large meals, or lying down shortly after eating. Frequent heartburn occurring more than twice a week may indicate GERD. Severe chest pain should always be evaluated promptly to rule out a heart attack.

ICD-10: R12

Hemodialysis is a treatment for kidney failure that uses a machine to filter waste products, excess fluid, and toxins from your blood when your kidneys can no longer do so. Blood is drawn from your body through a vascular access point, circulated through the dialysis machine, cleaned, and returned to your body. Most patients undergo sessions three times per week, each lasting three to five hours, typically at a dialysis center. You may feel fatigue or muscle cramps afterward. Hemodialysis is a life-sustaining therapy for people with end-stage kidney disease.

Hemoglobin is a protein found inside red blood cells that gives blood its red color and is responsible for carrying oxygen throughout the body. Each hemoglobin molecule can bind up to four oxygen molecules. Hemoglobin picks up oxygen in the lungs and releases it to tissues and organs, then carries carbon dioxide back to the lungs to be breathed out. A hemoglobin level is measured in a standard blood test called a complete blood count (CBC). Low hemoglobin is a sign of anemia and can cause fatigue, pale skin, and shortness of breath. Hemoglobin levels can be affected by iron deficiency, blood loss, kidney disease, or sickle cell disease.

The hemoglobin A1c (HbA1c) test measures your average blood sugar level over the past two to three months. Sugar in the blood sticks to hemoglobin inside red blood cells, and because those cells live about three months, the test captures a long-term picture rather than a single-day snapshot. A small blood sample is drawn from a vein or sometimes a finger-prick. No fasting is required. Doctors use HbA1c to diagnose diabetes (a result of 6.5% or higher) and to check whether people already living with diabetes are managing their blood sugar well. A result below 5.7% is considered normal.

Hemophilia is a rare genetic bleeding disorder in which the blood does not clot properly because it is missing or has low levels of certain clotting factors (factor VIII in hemophilia A, factor IX in hemophilia B). It affects mostly males. People with hemophilia can bleed for longer than usual after injury, and may experience spontaneous internal bleeding, especially into joints and muscles. Severity ranges from mild to severe. Treatment involves replacing the missing clotting factor through intravenous infusions, either on a preventive schedule or when bleeding occurs. Newer treatments include extended half-life factor products and non-factor therapies.

ICD-10: D66

Hemoptysis means coughing up blood or blood-tinged mucus from the lungs or airways. Even a small amount of blood in the sputum warrants medical evaluation. Causes range from a minor bronchial infection or irritation to serious conditions such as tuberculosis, lung cancer, pulmonary embolism, or severe pneumonia. Large amounts of blood, blood appearing alongside significant chest pain or shortness of breath, or hemoptysis in a person who smokes or has risk factors for lung disease requires emergency evaluation. Do not confuse hemoptysis with blood originating from the nose, mouth, or stomach.

ICD-10: R04

The hepatic artery is the blood vessel that carries oxygen-rich blood from the aorta — via the celiac artery — directly to the liver. The liver receives a dual blood supply: about twenty-five percent comes from the hepatic artery, and the remaining seventy-five percent comes from the portal vein carrying nutrient-rich blood from the digestive organs. The hepatic artery is critically important during liver transplant surgery and other hepatic procedures; surgeons must carefully preserve it so the donor liver receives adequate oxygen. When the hepatic artery is blocked — hepatic artery thrombosis — it is a serious complication, especially after liver transplant, because the bile ducts depend almost entirely on it for their blood supply.

Hepatitis B is a liver infection caused by the hepatitis B virus transmitted through blood, sexual contact, or from mother to baby during birth. Many adults with acute hepatitis B recover completely, but some develop chronic infection, which can lead to cirrhosis or liver cancer over time. Symptoms may include jaundice, fatigue, abdominal pain, dark urine, and nausea, though many people have no symptoms for years. An effective vaccine prevents hepatitis B. Chronic hepatitis B is treated with antiviral medications that suppress the virus and reduce liver damage. Regular liver function tests and ultrasound monitoring are important parts of ongoing care.

ICD-10: B18

Hepatitis C is a liver infection caused by the hepatitis C virus spread primarily through contact with infected blood, often through sharing needles or syringes. Many people have no symptoms for decades while the virus silently damages the liver. Chronic hepatitis C can cause cirrhosis, liver failure, and liver cancer. There is no vaccine for hepatitis C, but highly effective oral antiviral treatments called direct-acting antivirals can cure most infections in eight to twelve weeks. The CDC recommends that all adults be screened for hepatitis C at least once. Early detection and treatment prevent serious liver disease and halt transmission.

ICD-10: B18

A hernia occurs when an organ or fatty tissue squeezes through a weak spot in a surrounding muscle or connective tissue. Common types include inguinal hernia in the groin, hiatal hernia where the stomach bulges into the chest, umbilical hernia at the belly button, and incisional hernia at a surgical scar. Symptoms often include a visible bulge, pain or discomfort especially when bending or coughing, and a heavy feeling in the abdomen. Small hernias may be watched, but hernias that cause pain or grow larger usually require surgical repair. A strangulated hernia, where blood supply is cut off, is a medical emergency requiring immediate surgery.

ICD-10: K40

Hernia repair is surgery to fix a hernia, which occurs when an organ or tissue pushes through a weak spot in the surrounding muscle or connective tissue. Common types include inguinal (groin), umbilical (belly button), and hiatal hernias. The surgery pushes the protruding tissue back into place and strengthens the weak area, often with a synthetic mesh. Most hernia repairs are done laparoscopically under general anesthesia and take 30 to 90 minutes. Many patients go home the same day. Recovery involves avoiding heavy lifting for four to six weeks. Pain and swelling at the surgical site are normal in the first days after surgery.

A herniated disc occurs when the soft inner gel of a spinal disc pushes through a tear in its tougher outer layer, pressing on nearby nerves. This can cause pain, numbness, tingling, or weakness along the path of the affected nerve—often radiating down the arm or leg. The lumbar (lower back) and cervical (neck) regions are most commonly affected. Herniation can result from aging, injury, or heavy lifting. Most cases improve with rest, physical therapy, and anti-inflammatory medications, but severe cases may require epidural steroid injections or surgery.

ICD-10: M51

Hiccups are caused by involuntary contractions of the diaphragm followed by a sudden closure of the vocal cords, producing the characteristic sound. Brief episodes lasting a few minutes are common and usually triggered by eating too quickly, swallowing air, hot or spicy food, or alcohol. Hiccups that last more than 48 hours are called persistent hiccups and require medical evaluation. Hiccups lasting more than a month are called intractable. Persistent hiccups can be caused by gastroesophageal reflux, phrenic nerve irritation, central nervous system disorders, metabolic abnormalities, or medications. They can significantly impair eating, sleep, and quality of life.

ICD-10: R06

A High-Deductible Health Plan (HDHP) is a health insurance plan whose deductible meets IRS minimum thresholds—at least $1,650 for self-only coverage in 2025. Monthly premiums are typically lower than traditional plans, but you pay more out-of-pocket before insurance starts covering most services. The key advantage of an HDHP is eligibility to open and fund a Health Savings Account (HSA). Preventive care is usually covered at no cost before you meet your deductible. HDHPs appeal to healthy individuals who rarely need care or who want to build a tax-free medical savings reserve. Compare your expected annual costs carefully before choosing an HDHP over a lower-deductible plan.

The high-sensitivity CRP (hs-CRP) test measures very small amounts of C-reactive protein to assess chronic low-grade inflammation that standard CRP tests cannot detect. Doctors use hs-CRP alongside cholesterol measurements to evaluate cardiovascular risk. Research shows that even slightly elevated hs-CRP is associated with a higher risk of heart attack and stroke, even when cholesterol levels appear normal. Blood is drawn from a vein in your arm. Fasting is not required. A result below 1 mg/L indicates low cardiovascular risk; 1–3 mg/L is average risk; above 3 mg/L is high risk. Infections or inflammatory conditions can temporarily raise hs-CRP, so the test is most useful when you feel well.

Hip pain is discomfort in or around the hip joint, which connects the thigh bone to the pelvis. The pain may be felt in the groin, outer hip, buttock, or thigh. Common causes include arthritis, bursitis, muscle or tendon strain, labral tears, fractures (especially in older adults after a fall), and sciatica. Hip pain can make it difficult to walk, climb stairs, or put weight on that leg. Rest, anti-inflammatory medications, and physical therapy help many cases. Seek prompt care if the pain follows a fall or injury, the hip appears deformed, or you cannot move the leg or put any weight on it.

ICD-10: M25

Hip replacement is surgery to replace a damaged or worn hip joint with an artificial implant made of metal, ceramic, or plastic. It is most commonly performed for severe arthritis that causes chronic pain and limits mobility despite other treatments. The surgeon removes the damaged ball and socket of the hip joint and replaces them with prosthetic components. The procedure is done under general or spinal anesthesia and takes one to two hours. Hospital stays typically last one to three days. Physical therapy begins soon after surgery and continues for several weeks. Most patients experience significant pain relief and improved mobility. Full recovery may take three to six months.

HIPAA (Health Insurance Portability and Accountability Act) is a federal law enacted in 1996 that establishes national standards for the protection of health information. The Privacy Rule gives patients rights over their medical records, including the right to access, copy, and request corrections. The Security Rule requires covered entities to safeguard electronic health information. Providers must obtain patient authorization before sharing information with third parties in most circumstances. Violations can result in significant civil and criminal penalties.

HIV, or human immunodeficiency virus, attacks the immune system and can lead to AIDS, acquired immunodeficiency syndrome, the most advanced stage of HIV infection. HIV spreads through contact with certain body fluids, mainly blood, semen, vaginal fluids, and breast milk. Without treatment, HIV progressively damages the immune system, making the body vulnerable to infections and cancers. Modern antiretroviral therapy allows people with HIV to live long, healthy lives and reduces the risk of transmitting the virus. Pre-exposure prophylaxis, or PrEP, is available to prevent HIV in high-risk individuals. Regular testing and early treatment are key to managing this infection.

ICD-10: B20

Hives are raised, itchy welts on the skin that appear suddenly and can occur anywhere on the body. They are usually caused by an allergic reaction to foods, medications, insect stings, or environmental triggers such as pollen or latex. Stress and infections can also cause hives. Most cases resolve within hours to a few days. Seek emergency care if hives are accompanied by swelling of the face, lips, or throat, difficulty breathing, or dizziness, as these signs may indicate anaphylaxis, a life-threatening allergic reaction that requires immediate treatment with epinephrine.

ICD-10: L50

An HMO (Health Maintenance Organization) is an insurance plan type that requires members to choose a primary care provider and obtain referrals to see specialists. HMOs typically only cover care from in-network providers except in emergencies. They usually have lower premiums and out-of-pocket costs compared to PPO plans, but less flexibility in provider choice. Members must use HMO-designated facilities for non-emergency care to have costs covered. HMOs emphasize coordinated, preventive care.

A Holter monitor is a portable device that continuously records your heart's electrical activity for 24 to 48 hours — or sometimes up to 14 days — while you go about your daily routine. Small sticky electrodes are attached to your chest and connected by wires to a small recorder that clips to your belt or fits in your pocket. You keep a diary of your activities and any symptoms you notice, such as palpitations or dizziness. You should avoid showering or bathing with the device on. After the monitoring period, you return the device to your doctor, who reviews the recording for irregular heart rhythms that may not show up during a brief office EKG. No radiation is involved.

Home health care refers to skilled medical services provided in a patient's home by licensed professionals, including nurses, physical therapists, occupational therapists, and speech therapists. These services are distinct from non-medical home care (such as housekeeping or companion services). Medicare Part A or B may cover home health care when a patient is homebound, under a physician's care, and receiving skilled services. Coverage is based on medical necessity and is subject to prior authorization by many private insurers.

Hormone therapy involves medications that add, block, or alter hormone levels in the body. It is used in several contexts: menopausal hormone therapy (MHT) replaces estrogen and progesterone to relieve menopause symptoms; androgen deprivation therapy (ADT) reduces testosterone to treat prostate cancer; and thyroid hormone replacement treats hypothyroidism. Hormone therapy may come as pills, patches, gels, injections, or implants. Risks and benefits vary by type and individual health history — for example, estrogen therapy carries different risks for women with a history of breast cancer. Always review your complete health history with your doctor before starting any hormone therapy.

Hospice care provides specialized comfort-focused medical care for individuals with a terminal illness and a life expectancy of six months or less, as certified by two physicians. Hospice prioritizes quality of life and symptom management over curative treatment. Medicare Part A fully covers hospice care (including medications related to the terminal diagnosis, nursing, aide services, and bereavement counseling for families) when care is provided by a Medicare-certified hospice program and the patient elects the hospice benefit. Patients can leave hospice and return to curative care at any time.

Hospital admission means you are formally checked in as an inpatient and will stay overnight or longer for medical care. A physician must write an order to admit you. Your care team, room assignment, and insurance billing all change after admission. There is an important distinction between inpatient admission and observation status, which affects your Medicare or insurance costs significantly. When admitted, you will be asked about your insurance, next of kin, and advance directives. You have the right to know your admission status. Ask your doctor or nurse whether you are admitted as an inpatient or under observation, as this affects your financial responsibility.

A hospital bed is a specialized adjustable bed designed to support patient care in a hospital setting. Unlike a home bed, it can be raised or lowered electronically, tilted at various angles, and features side rails to prevent falls. Hospital beds can accommodate medical equipment attachments, drainage bags, and IV poles. The head and foot of the bed can be adjusted separately. Patients should ask nursing staff before adjusting the bed and should use the call button if they need to get up to avoid falling. Hospital beds may also have built-in weight scales and pressure-relief mattresses to prevent bedsores in patients who cannot move easily.

Hospital discharge instructions are written directions given to patients when they leave the hospital. They explain what happened during your stay, what medications to take and when, which activities to avoid while you recover, warning signs that should prompt you to seek emergency care again, and when to schedule follow-up appointments with your doctor. These instructions are legally required and must be provided in a language you understand. Read them carefully before leaving, ask questions about anything unclear, and keep them accessible at home. Following discharge instructions reduces the risk of complications and readmission.

Hospital financial assistance programs, also called charity care programs, provide free or discounted care to patients who cannot pay their medical bills. Under the ACA, non-profit hospitals must have written financial assistance policies (FAPs), publicize them, make plain-language summaries available, and not charge patients who qualify for assistance more than the amounts generally billed to insured patients. Applications are typically income-based. Hospitals must provide financial assistance applications before sending bills to collections.

A hospital transfer occurs when a patient is moved from one hospital to another for a higher level of care, specialized treatment, or because the current hospital does not have the needed resources. For example, a patient with a severe stroke may be transferred to a hospital with a specialized stroke unit or neurosurgery capabilities. Transfers also happen when a patient stabilizes and no longer needs a high-level facility. The transferring team sends your records and communicates your condition to the receiving hospital. By US law (EMTALA), hospitals must stabilize patients before transferring. Ask why a transfer is recommended and what it means for your care.

A hospitalist is a physician who specializes in the care of patients during a hospital admission. Unlike patients' regular outpatient doctors, hospitalists are based in the hospital and manage the full course of inpatient care — coordinating tests, medications, specialist consultations, and discharge planning. Patients admitted to a hospital are typically cared for by the on-call hospitalist rather than their own primary care provider. Hospitalists are generally in-network for the hospital but patients should confirm this to avoid surprise billing.

Hot flashes are sudden feelings of intense warmth, often spreading over the face, neck, and chest, followed by sweating and sometimes chills. They most commonly occur during perimenopause and menopause due to declining estrogen levels. They can also be triggered by certain medications, chemotherapy, stress, hot beverages, and spicy food. In men, hot flashes can occur during androgen deprivation therapy for prostate cancer. Hot flashes are generally not medically dangerous but can disrupt sleep and quality of life. Talk to your doctor about management options, including hormone therapy, non-hormonal medications, and lifestyle changes. Record frequency and severity to guide treatment decisions.

ICD-10: N95

The HPV test detects the presence of human papillomavirus, a sexually transmitted virus that can infect the cervix and increase the risk of cervical cancer. High-risk HPV strains (especially HPV 16 and 18) are responsible for most cervical cancers. The test uses a sample collected the same way as a Pap smear — a clinician uses a small brush to swab cells from the cervix during a pelvic exam. The HPV test is often done at the same time as a Pap smear (co-testing). Women aged 30–65 can do co-testing every five years. A positive HPV test does not mean you have cancer, but it signals a need for closer follow-up.

A Health Reimbursement Arrangement (HRA) is an employer-funded account that reimburses you tax-free for qualified out-of-pocket medical expenses and, in some plan designs, individual insurance premiums. Only your employer can contribute—you cannot add your own money. Common types include the Qualified Small Employer HRA (QSEHRA), which lets small businesses reimburse employees for individual insurance costs, and the Individual Coverage HRA (ICHRA), which can replace traditional group coverage. Unused funds may or may not roll over depending on plan rules. HRA reimbursements are excluded from your taxable income and can cover costs your health plan does not pay, such as deductibles or copays.

The Health Resources and Services Administration (HRSA) is the primary federal agency for improving healthcare access to people who are uninsured, isolated, or medically vulnerable. HRSA funds Federally Qualified Health Centers (FQHCs), operates the National Health Service Corps, oversees organ donation and transplantation, manages the Ryan White HIV/AIDS Program, and administers the Vaccine Injury Compensation Program. HRSA's Find a Health Center tool (findahealthcenter.hrsa.gov) locates sliding-fee community health centers across the US.

A Health Savings Account (HSA) is a tax-advantaged savings account available to individuals enrolled in a qualifying HDHP. Contributions are pre-tax (or tax-deductible), earnings grow tax-free, and withdrawals for qualified medical expenses are also tax-free — a triple tax benefit. HSA funds roll over year to year and can be invested. After age 65, funds can be withdrawn for any purpose (taxed as income, like a traditional IRA). Annual contribution limits are set by the IRS.

An HSA-eligible expense is a medical cost that qualifies for tax-free payment or reimbursement from a Health Savings Account. The list mirrors FSA-eligible expenses but includes some additional items. After age 65, HSA funds can be used for Medicare premiums (Part B, Part D, Medicare Advantage). HSA funds cannot be used for most health insurance premiums (with exceptions for COBRA, long-term care insurance, and certain continuation coverage). IRS Publication 502 provides the authoritative list. Using HSA funds for non-qualified expenses results in income taxes plus a 20% penalty if under age 65.

The humerus is the long bone in your upper arm, running from your shoulder down to your elbow. At the top, it forms the ball of the ball-and-socket shoulder joint, and at the bottom, it connects with the radius and ulna to form the elbow joint. The humerus allows your arm to move in many directions and provides attachment points for the powerful muscles of your shoulder and upper arm. Fractures of the humerus can occur from falls, direct blows, or throwing injuries. Breaks near the top, called proximal humerus fractures, are especially common in older adults after falls.

Hyperlipidemia means abnormally high levels of fats (lipids) in the blood, including cholesterol and triglycerides. High LDL (bad) cholesterol and triglycerides contribute to plaque buildup in arteries, raising the risk of heart attack and stroke. It usually causes no symptoms, so it is detected through a blood test called a lipid panel. Risk factors include unhealthy diet, physical inactivity, obesity, genetics, and certain medications. Treatment begins with diet and exercise changes. When lifestyle changes are not enough, doctors may prescribe statins or other cholesterol-lowering medications to reduce cardiovascular risk.

ICD-10: E78

Hypermobility syndrome occurs when joints move beyond their normal range of motion due to lax connective tissue, causing pain, instability, and frequent injuries such as sprains and dislocations. It is part of a spectrum that includes hypermobile Ehlers-Danlos syndrome (hEDS). People may notice their joints click, give way, or dislocate easily. Chronic widespread pain, fatigue, and poor proprioception are common. Daily activities like standing, walking, or gripping can become painful. Treatment centers on physical therapy to build stabilizing muscle strength, joint protection strategies, pain management, and avoiding activities that overload unstable joints.

ICD-10: M35

Hypertension, or high blood pressure, means the force of blood pushing against your artery walls is consistently too high. Normal blood pressure is below 120/80 mmHg; readings of 130/80 or higher are considered high. Over time, untreated high blood pressure damages blood vessels and increases risk of heart attack, stroke, and kidney failure. It rarely causes symptoms, so it is often called the 'silent killer.' Treatment typically includes lifestyle changes such as reducing salt intake and exercising, along with medications prescribed by your doctor.

ICD-10: I10

Hyperthyroidism occurs when the thyroid gland produces too much thyroid hormone, speeding up the body's metabolism. The most common cause is an autoimmune condition called Graves' disease. Symptoms include rapid or irregular heartbeat, weight loss despite increased appetite, heat intolerance, sweating, tremors, anxiety, and trouble sleeping. It is diagnosed with blood tests that measure thyroid hormone levels. If untreated, hyperthyroidism can lead to serious heart problems and bone loss. Treatment options include anti-thyroid medications, radioactive iodine therapy, or in some cases surgery to remove part or all of the thyroid gland.

ICD-10: E05

Hypoglycemia is a condition where blood sugar (glucose) levels drop below the normal range, typically below 70 mg/dL. Blood sugar is the main source of energy for the brain and body. Low blood sugar causes symptoms such as shakiness, sweating, dizziness, confusion, rapid heartbeat, and in severe cases seizures or loss of consciousness. It most commonly occurs in people with diabetes who take insulin or certain diabetes medications. Treatment for a mild episode involves consuming fast-acting carbohydrates such as juice or glucose tablets. Severe episodes may require a glucagon injection or emergency medical care. Identifying patterns that trigger episodes helps prevent recurrence.

ICD-10: E16

The hypothalamus is a small but vital region of the brain located just above the brainstem and below the thalamus. It acts as the body's main control center for maintaining balance and stability, a process called homeostasis. The hypothalamus regulates body temperature, hunger, thirst, sleep cycles, heart rate, blood pressure, and the release of hormones from the pituitary gland. It links your nervous system to your endocrine (hormone) system. When your body gets too hot, the hypothalamus triggers sweating. When blood sugar drops, it signals hunger. Damage to the hypothalamus can cause problems with temperature regulation, abnormal hunger or thirst, or hormone disorders.

Hypothyroidism is a condition in which the thyroid gland, located in the front of the neck, does not produce enough thyroid hormone. Thyroid hormone regulates metabolism, which is how the body uses energy. When levels are too low, body processes slow down. Symptoms include fatigue, weight gain, feeling cold, dry skin, hair loss, constipation, and depression. It is diagnosed with a blood test measuring TSH levels. The most common cause is an autoimmune condition called Hashimoto's disease. Treatment is a daily oral medication called levothyroxine that replaces the missing hormone, and most people feel much better once the dose is properly adjusted.

ICD-10: E03

A hysterectomy is surgery to remove the uterus. The cervix, ovaries, and fallopian tubes may also be removed depending on the reason for the procedure. It is performed for conditions such as uterine fibroids, endometriosis, uterine prolapse, abnormal bleeding, or cancer. After a hysterectomy, menstrual periods stop permanently and pregnancy is no longer possible. The surgery may be done through the abdomen, vagina, or laparoscopically. Recovery ranges from two to six weeks depending on the approach. If the ovaries are removed, menopause begins immediately. Your surgeon will discuss hormone therapy options and what to expect during recovery.

The International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM) is the US standard code set for diagnosis reporting on medical claims. Maintained by the CDC, it assigns alphanumeric codes (e.g., J06.9 for acute upper respiratory infection) to every recognized diagnosis. As of FY2027, ICD-10-CM contains over 74,000 billable codes. Providers must use the correct ICD-10-CM code on insurance claims for the claim to be processed.

In healthcare, identification refers to documents—such as a driver's license, passport, state ID card, or insurance card—that providers and insurers require to confirm who you are and verify your eligibility when you register for services. Presenting your insurance card at every visit allows the provider to bill your plan correctly and helps prevent billing errors. By federal law under EMTALA, emergency rooms must provide a medical screening examination regardless of whether you have identification. Some community health centers and safety-net clinics accept alternate identification to help patients without standard government-issued ID access care without delay.

The ileum is the third and final section of the small intestine, following the duodenum and jejunum. It is about twelve feet long and sits in the lower right part of the abdomen. The ileum is responsible for absorbing vitamin B12 and bile acids — substances the body recycles to make new bile — as well as any nutrients not absorbed in the earlier sections of the small intestine. The ileum connects to the large intestine at a valve called the ileocecal valve, which controls the flow of material into the colon and prevents backward flow. Crohn's disease commonly affects the ileum, causing inflammation, pain, and diarrhea. Surgery that removes part of the ileum can affect the body's ability to absorb B12 and certain fats.

Immigration status is your legal classification under federal law—such as U.S. citizen, lawful permanent resident, refugee, asylum seeker, or undocumented immigrant—which directly affects your eligibility for federal health programs. Lawful permanent residents who have lived in the U.S. for at least five years may qualify for full Medicaid. Refugees and asylees often have immediate eligibility. Undocumented immigrants are generally not eligible for federally funded Medicaid but may access emergency Medicaid, Federally Qualified Health Centers on a sliding-fee basis, and some state-funded programs. Emergency rooms must perform a medical screening examination for all patients regardless of immigration status.

Immunization is the process of protecting a person against an infectious disease, most commonly by administering a vaccine. It works by stimulating the immune system to recognize and fight a specific virus or bacteria without causing the actual disease. Childhood immunization schedules recommended by the CDC cover diseases such as measles, mumps, rubella, polio, and hepatitis. Adults may also need boosters or new vaccines throughout life, including flu shots and shingles vaccines. Immunization is generally quick, involving a brief injection, and is one of the most cost-effective public health interventions for preventing serious illness and its complications.

The immunization schedule is the official timetable from the Centers for Disease Control and Prevention (CDC) and the American Academy of Pediatrics (AAP) that tells parents when to give each vaccine to their child. Starting at birth with the hepatitis B vaccine, children receive vaccines at each well-child visit to protect against diseases like measles, polio, whooping cough, and chickenpox. Following the recommended schedule provides the best protection at the ages children are most vulnerable. Most states require children to be up to date before starting school. Your child's immunization record can be kept digitally through your state's registry.

ICD-10: Z23

Immunosuppressants are medications that reduce the activity of the immune system. They are used to prevent organ rejection after transplants and to treat autoimmune diseases such as rheumatoid arthritis, lupus, multiple sclerosis, and inflammatory bowel disease. Common immunosuppressants include tacrolimus, cyclosporine, mycophenolate, azathioprine, and methotrexate. Because they lower immune defenses, patients are at higher risk of infections — report any signs of infection to your doctor immediately. Regular blood tests are needed to monitor drug levels and organ function. Avoid live vaccines while on immunosuppressants. Sun protection is important, as some immunosuppressants increase the risk of skin cancer.

Immunotherapy is a cancer treatment that helps your own immune system recognize and attack cancer cells. Types include checkpoint inhibitors, CAR-T cell therapy, and monoclonal antibodies. It is typically given by IV infusion in a clinic, sometimes in combination with chemotherapy. Sessions can range from thirty minutes to several hours, and treatment schedules vary widely. Side effects may include fatigue, skin rash, diarrhea, or immune-related inflammation. Immunotherapy has become a standard option for many cancers, including melanoma, lung cancer, and certain blood cancers, often producing longer-lasting responses than traditional treatments.

An in-network provider is a doctor, hospital, pharmacy, or other healthcare provider that has a contract with your insurance plan to provide services at negotiated rates. Using in-network providers results in lower cost-sharing — lower copays, coinsurance, and deductibles — compared to out-of-network care. Network directories are available through insurer websites, but should be verified by calling the provider directly, as directories are not always current.

Income-based eligibility means that whether you qualify for a health program—such as Medicaid, CHIP, or an Advance Premium Tax Credit on the ACA marketplace—depends on your household income measured as a percentage of the Federal Poverty Level (FPL). Medicaid expansion covers adults with incomes up to 138 percent of the FPL in participating states, while marketplace subsidies scale with income. Eligibility is calculated using Modified Adjusted Gross Income (MAGI). When you apply, you may need to provide pay stubs, a recent tax return, or a self-attestation of projected annual income. Reporting income changes during the year helps you avoid owing back subsidies at tax time.

Indemnity insurance (also called fee-for-service insurance or traditional health insurance) allows you to visit any doctor or hospital without a network restriction. You pay for services upfront and then submit a claim for reimbursement, or your provider bills the insurer directly. The insurer reimburses a percentage of the allowed charge. Indemnity plans typically have higher premiums and may require more paperwork. They offer maximum flexibility for patients who travel frequently or have long-standing relationships with specific providers outside any network. These plans are less common today but still available in some markets.

Independent Dispute Resolution (IDR) is a federal arbitration process created by the No Surprises Act where an out-of-network provider and a health insurer submit their payment disagreement to a neutral third-party arbitrator when they cannot agree on reimbursement. The arbitrator selects one of the two submitted offers—using the qualifying payment amount as a benchmark—without splitting the difference. Patients are shielded from this dispute and may not be balance-billed beyond their in-network cost-sharing responsibility. The federal IDR portal manages all submissions. This process replaced the prior practice of providers billing patients directly for the disputed balance after insurance paid.

An Independent Review Organization (IRO) is an accredited third-party company that conducts external reviews of health plan coverage denials after you have exhausted internal appeals. The IRO's decision is binding on the health plan—it cannot ignore or override it. Federal law requires most employer-sponsored and ACA marketplace plans to offer external review through a certified IRO. You typically have 60 days from a final internal denial to request an external review. For urgent situations where waiting could seriously harm your health, expedited external reviews must be completed within 72 hours. The IRO external review process is generally free to you as a patient.

Influenza, commonly called the flu, is a contagious respiratory illness caused by influenza viruses. It spreads through respiratory droplets and causes sudden onset of fever, chills, muscle aches, headache, fatigue, sore throat, and cough. Symptoms are usually more severe than a common cold. Most healthy adults recover within one to two weeks, but the flu can cause serious complications such as pneumonia in young children, elderly adults, and people with chronic conditions. Antiviral medications like oseltamivir can shorten illness duration if taken early. Annual flu vaccination is the best prevention strategy.

ICD-10: J11

Informed consent is the process by which a healthcare provider explains a proposed treatment, procedure, or research participation to a patient, including its purpose, risks, benefits, and alternatives, so the patient can make a voluntary and educated decision. Patients must have decision-making capacity and the opportunity to ask questions. Consent must be obtained without coercion. For research participation, informed consent is required by federal regulations and overseen by an Institutional Review Board (IRB). Patients can withdraw consent at any time.

The Initial Enrollment Period (IEP) is the seven-month window during which you first become eligible for Medicare. It starts three months before your 65th birthday month, includes your birthday month, and ends three months after. Enrolling in Part B during the first three months of your IEP means coverage starts on the first day of your birthday month; waiting until later delays your start date. Missing your IEP without qualifying for a Special Enrollment Period—typically available when you have active employer coverage—can result in permanent late-enrollment penalties added to your monthly Part B premium. Part A is generally premium-free for those who worked at least 10 years.

An injectable medication is a drug administered by injection into a vein, muscle, or the fatty tissue under the skin. Injectables are used when a drug cannot be taken by mouth, needs to work very quickly, or must bypass the digestive system to remain effective. Some injectables are given in a clinical setting by a provider, while others, such as insulin, certain weight-loss drugs, and biologic treatments, are designed for self-administration at home using a prefilled syringe or auto-injector pen. Proper injection technique, needle safety, and site rotation are important to prevent bruising, infection, or lumps. Your pharmacist or nurse can train you on safe self-injection.

Inpatient care refers to treatment requiring a formal hospital admission, where the patient stays overnight or for multiple days. Inpatient admissions are covered under Medicare Part A and by most private insurance plans, subject to deductibles and coinsurance. The decision to admit a patient as inpatient (versus 'observation status') significantly affects coverage and cost — observation status is classified as outpatient care and may result in higher patient costs, particularly for subsequent skilled nursing facility care under Medicare.

Inpatient psychiatric care is 24-hour hospital-level mental health treatment for people experiencing a serious mental health crisis — such as thoughts of suicide with intent, severe psychosis, or a mental health emergency that cannot be safely managed in the community. During inpatient care, a person stays in a supervised psychiatric unit where they receive evaluation, stabilization, medication adjustment, therapy, and discharge planning. The goal is to stabilize the person safely and connect them to step-down care. Inpatient stays are typically short — averaging several days. Under federal mental health parity law, insurance plans that cover medical inpatient stays must also cover psychiatric inpatient stays on equal terms. Contact your insurer for prior authorization requirements.

Insomnia is difficulty falling asleep, staying asleep, or waking too early and being unable to return to sleep. It is one of the most common sleep complaints. Short-term insomnia often results from stress, a disrupted schedule, caffeine, or jet lag. Chronic insomnia lasting three or more nights a week for three months or longer may be linked to anxiety, depression, chronic pain, sleep apnea, or medications. Poor sleep impairs concentration, mood, and overall health. Treatment options include sleep hygiene improvements, cognitive behavioral therapy for insomnia, and in some cases short-term medication under medical supervision.

ICD-10: G47

An Institutional Review Board (IRB) is a committee required by federal law to review, approve, and monitor research involving human subjects—including clinical trials—to ensure participant safety and ethical standards are upheld. Before a clinical study can enroll patients, the IRB evaluates the study's risk-benefit balance, informed consent procedures, and privacy protections. Participants in any federally regulated or FDA-overseen research have the right to read the IRB approval documentation and to withdraw from the study at any time without penalty or loss of ongoing medical care. Hospitals, universities, and independent organizations operate IRBs; many large studies use a centralized IRB.

Insulin is a hormone medication that helps the body use sugar (glucose) for energy by allowing it to enter cells. People with type 1 diabetes must take insulin because their body makes none. Many people with type 2 diabetes also use insulin when other medications are not enough. Insulin comes in different types — rapid-acting, short-acting, intermediate, and long-acting — each with a different timing profile. It is typically injected under the skin or delivered through an insulin pump. Store unopened insulin in the refrigerator; opened vials can be kept at room temperature for up to 30 days. Never skip doses without guidance, as this can cause dangerously high blood sugar.

An insurance claim is a formal request submitted to an insurer for payment of a covered health service. For in-network care, the provider typically submits the claim directly on behalf of the patient. For out-of-network care, the patient may need to submit the claim themselves with supporting documentation. Claims are reviewed for eligibility, coverage, and medical necessity. If a claim is denied, patients have the right to appeal — first through the insurer's internal process, then through external review by an independent organization.

The intensive care unit (ICU) is a specialized hospital ward for patients who are critically ill and need continuous, close monitoring and advanced life support. Nurses and doctors in the ICU manage life-threatening conditions such as organ failure, severe infections, major surgeries, and serious injuries. Equipment in the ICU includes heart monitors, mechanical ventilators, and IV infusion pumps. Visiting hours are often limited. ICU care is more intensive and costly than general ward care. Being admitted to the ICU means your condition is serious and requires around-the-clock specialized nursing and physician attention.

An interchangeable biosimilar is a biologic medication the FDA has determined can be substituted for its reference brand-name biologic at the pharmacy without the prescriber's intervention—similar to how generic drugs substitute for brand-name pills. To earn this designation, the manufacturer must prove that switching back and forth between the two products will not produce worse outcomes or safety concerns compared to staying on one. Pharmacists in most states can substitute an interchangeable biosimilar at the point of dispensing. Because biosimilars are typically priced lower than the original biologic, this substitution can significantly reduce your drug costs or move you to a lower copay tier.

The intercostal muscles are the muscles that fill the spaces between the ribs — intercostal means between the ribs. There are three layers of these muscles on each side of the chest. They play a vital role in breathing: the external intercostal muscles help expand the rib cage when you inhale, drawing air into the lungs, while the internal intercostals help compress the rib cage when you exhale forcefully. Between each pair of ribs runs an intercostal nerve, artery, and vein. Shingles — the reactivation of the chickenpox virus — can affect the intercostal nerves and cause a painful, burning rash that follows the line of a rib, a condition called postherpetic neuralgia.

An internal appeal is a formal request you submit to your health insurance plan asking it to reconsider a denial of coverage, prior authorization, or payment. It is the first required step in the appeals process—you must generally exhaust internal appeals before seeking an external review by an Independent Review Organization. Federal law requires plans to decide standard internal appeals within 30 days for pre-service decisions and 60 days for payment disputes. Urgent or expedited appeals must be resolved within 72 hours. During the appeal, you can submit supporting documents—physician letters, medical records, clinical guidelines—that strengthen your case. Keep copies of everything you submit.

The Interstate Medical Licensure Compact (IMLC) is an agreement among participating U.S. states that streamlines how licensed physicians obtain medical licenses in multiple member states. Instead of applying separately to each state, a qualifying doctor applies once through the compact and receives licenses in all chosen member states simultaneously. This matters for telehealth because physicians must typically hold a license in the state where the patient is located. If you receive care from an out-of-state telehealth provider, confirm they are licensed in your state—IMLC participation makes that more common. A parallel Nurse Licensure Compact exists for registered nurses.

Intervertebral discs are the cushion-like pads that sit between each of the bones in your spine. Each disc has a tough outer ring and a softer, gel-like center. They act as shock absorbers, protecting the vertebrae from impact and allowing your spine to bend and flex. When a disc is damaged — through injury, aging, or repetitive strain — its soft inner material can push outward, a condition called a herniated or slipped disc. This can press on nearby nerves and cause pain, tingling, or numbness in the back, neck, arms, or legs. Discs naturally lose water and flexibility with age.

Intubation is the placement of a flexible tube (endotracheal tube) through the mouth or nose down into the airway (trachea) to help a patient breathe. It is performed when a patient cannot breathe adequately on their own due to unconsciousness, respiratory failure, or during surgery. The tube is then connected to a mechanical ventilator. Intubation is a serious emergency procedure but often life-saving. The patient cannot speak while intubated. Doctors and nurses will communicate with intubated patients using yes/no gestures or writing boards. Intubation is typically temporary, with the tube removed once the patient can breathe independently.

Involuntary movements are motions the body makes without conscious control. They include tremors, tics, chorea (irregular dancing or writhing movements), myoclonus (brief muscle jerks), and dystonia (sustained abnormal postures). Causes range from medication side effects and caffeine to Parkinson's disease, Huntington's disease, and Tourette syndrome. Some brief jerks at sleep onset are normal. Involuntary movements that interfere with daily life, worsen over time, or appear suddenly require medical evaluation. Call your doctor for an appointment; call 911 if movements accompany loss of consciousness, confusion, or signs of stroke. Recording the movements on video can help your doctor evaluate them more accurately.

ICD-10: R25

An Institutional Review Board (IRB) is an independent committee that reviews and approves research involving human subjects to ensure participant rights, safety, and welfare are protected. IRBs evaluate study protocols, informed consent documents, and ongoing studies. Federal regulations require IRB oversight for research conducted or funded by federal agencies and for studies supporting FDA submissions. IRBs have the authority to approve, modify, or reject research proposals. Members typically include scientists, non-scientists, and community representatives.

The iris is the colored ring in your eye — the part that makes eyes appear blue, green, brown, or hazel. It is located behind the cornea and in front of the lens. The iris contains tiny muscles that control the size of the pupil, the black circle in its center. In bright light, the iris makes the pupil smaller to let in less light, protecting the retina. In dim light, the iris opens the pupil wider to let in more light. This process happens automatically. Inflammation of the iris, called iritis or anterior uveitis, causes eye pain, redness, and light sensitivity. It can be linked to autoimmune conditions and requires prompt treatment to prevent complications.

IRMAA stands for Income-Related Monthly Adjustment Amount—the extra surcharge added to your Medicare Part B and Part D premiums when your income from two years ago exceeds certain IRS thresholds. In 2025, single filers with income above $106,000 pay more than the standard Part B premium. Surcharges are tiered: the higher your income, the larger the add-on. If your income has dropped significantly—because of retirement, a spouse's death, divorce, or loss of pension income—you can ask Social Security to use a more recent tax year by filing Form SSA-44 with supporting documents. Social Security sends an IRMAA determination letter each fall for the following year.

Iron deficiency anemia is the most common type of anemia, occurring when the body does not have enough iron to make adequate hemoglobin. Hemoglobin is the protein in red blood cells that carries oxygen. Without enough iron, red blood cells become smaller and carry less oxygen. Symptoms include fatigue, weakness, pale skin, brittle nails, cold hands and feet, headaches, and unusual cravings for non-food items (pica). Common causes include poor dietary intake of iron, blood loss from heavy periods or internal bleeding, and pregnancy. Treatment involves iron supplements or IV iron infusions, and identifying and addressing the underlying cause of iron loss.

ICD-10: D50

Iron studies are a group of blood tests that measure different aspects of how your body handles iron. The panel typically includes serum iron (iron circulating in blood), transferrin or total iron-binding capacity (TIBC, which measures how much iron your blood can carry), transferrin saturation (the percentage of transferrin that is carrying iron), and ferritin (stored iron). Together these values help diagnose the cause and type of anemia — whether it is iron deficiency anemia, anemia of chronic disease, or iron overload. Blood is drawn from a vein in your arm. Fasting for eight to twelve hours before the draw is often recommended for the most accurate serum iron result.

An irregular heartbeat (arrhythmia) means the heart is not beating in a steady, normal rhythm. You may feel your heart flutter, skip, or pound erratically. The most common arrhythmia is atrial fibrillation (AFib), which significantly raises stroke risk. Other types include premature beats, supraventricular tachycardia (SVT), and life-threatening ventricular fibrillation. Brief, occasional irregular beats in an otherwise healthy person are usually harmless. Call 911 if an irregular heartbeat is accompanied by chest pain, fainting, severe shortness of breath, or sudden weakness. Diagnosis is made by an ECG. Treatment depends on the type and severity of the arrhythmia.

ICD-10: R00

Irritability is a state of being easily annoyed, frustrated, or angered by things that would not normally bother you. It can be a short-term response to stress, lack of sleep, pain, or hunger. Persistent irritability may be a symptom of depression, anxiety, bipolar disorder, premenstrual syndrome, thyroid disorders, or chronic pain conditions. In children, irritability can be a sign of infection or an underlying behavioral condition. It is important to discuss prolonged irritability with a healthcare provider, as it can affect relationships and quality of life, and may indicate a treatable mental health or medical condition.

Irritable bowel syndrome is a common chronic condition affecting the large intestine, causing abdominal pain, bloating, gas, and changes in bowel habits such as diarrhea, constipation, or alternating between the two. Unlike inflammatory bowel diseases such as Crohn's or ulcerative colitis, IBS does not cause changes in bowel tissue or increase the risk of colorectal cancer. The cause is not well understood but may involve abnormal gut muscle contractions, nervous system issues, gut microbiome changes, and stress. Treatment focuses on managing symptoms through dietary changes such as a low-FODMAP diet, stress management, medications, and fiber supplements. Triggers vary from person to person.

ICD-10: K58

IRS Publication 502, Medical and Dental Expenses, is a free IRS guide explaining which healthcare costs you may deduct on Schedule A of your federal income tax return. To claim the deduction, your unreimbursed medical expenses must exceed 7.5 percent of your adjusted gross income. Eligible costs include self-paid health insurance premiums, prescription drugs, dental and vision care, certain long-term care services, and transportation to medical appointments. The publication also clarifies what qualifies for reimbursement from an HSA, FSA, or HRA. Updated each tax year, it is available free at IRS.gov and is essential reading if you had high out-of-pocket medical costs in the prior year.

Itching, also called pruritus, is an uncomfortable sensation that prompts the urge to scratch. It can affect a small area or the whole body. Common causes include dry skin, eczema, psoriasis, allergic reactions, insect bites, and skin infections. Itching without a visible rash may signal internal conditions such as liver disease, kidney failure, thyroid disorders, or certain cancers. Prolonged or severe itching should be evaluated by a healthcare provider. Treatment depends on the cause and may include moisturizers, antihistamines, corticosteroid creams, or treatment of an underlying systemic condition.

ICD-10: L29

An itemized medical bill lists every charge for a healthcare encounter individually — each procedure, medication, supply, and service with its corresponding billing code (CPT or HCPCS code) and charge amount. Patients have the right to request an itemized bill from any provider. Reviewing itemized bills is important for identifying billing errors, duplicate charges, or services never received. Common billing errors include upcoding (billing for more complex services than provided) and unbundling (billing procedure components separately instead of as a package).

IV access (intravenous access) refers to placing a small plastic catheter (needle) into a vein—usually in the arm, hand, or wrist—to allow healthcare providers to deliver medications, fluids, blood products, or contrast dye directly into the bloodstream. IV access is one of the first things established in the emergency room. It may feel like a pinch when inserted. A peripheral IV is the most common type and is placed by a nurse. Once placed, medications can be given very quickly during emergencies. If peripheral veins are difficult to access, a central venous catheter may be placed instead. Keep the IV site clean and tell staff if it becomes painful or swollen.

Intravenous (IV) fluids are liquids delivered directly into a vein through a small needle or catheter to restore hydration, correct electrolyte imbalances, deliver medications, or provide nutrition when oral intake is not possible. Common solutions include saline, dextrose, and lactated Ringer's. IV fluids are used in hospitals, emergency rooms, infusion centers, and sometimes at home. They may be administered continuously over hours or as a single rapid bolus. Nurses monitor the infusion rate and your response. IV fluid therapy is fundamental in treating dehydration, infections requiring IV antibiotics, and many acute medical conditions.

Jaundice is a yellowing of the skin and the whites of the eyes caused by a buildup of bilirubin, a yellow pigment produced when red blood cells break down. Normally the liver processes bilirubin for excretion, but when the liver is diseased or the bile ducts are blocked, bilirubin accumulates. Common causes include hepatitis, cirrhosis, gallstones, bile duct obstruction, and hemolytic anemia. Jaundice is always a significant finding. It may also be accompanied by dark urine, pale stools, itching, and abdominal pain. New jaundice in an adult should be evaluated by a doctor promptly, usually the same day.

ICD-10: R17

The jejunum is the middle section of the small intestine, located between the duodenum — which connects to the stomach — and the ileum — which connects to the large intestine. It is about eight feet long and makes up about two-fifths of the total length of the small intestine. The jejunum is responsible for absorbing most of the nutrients from digested food, including sugars, amino acids from proteins, and fatty acids. Its inner walls are covered with finger-like projections called villi and even smaller microvilli that create a huge surface area for absorption. Celiac disease — an immune reaction to gluten — primarily damages the jejunum's lining, reducing nutrient absorption and causing diarrhea, bloating, and malnutrition.

A joint injection is an outpatient procedure in which medication is injected directly into a joint space to relieve pain and inflammation. Common medications used include corticosteroids (anti-inflammatory steroids) and hyaluronic acid (a lubricating gel). Joint injections are used for arthritis, bursitis, tendinitis, and joint injuries in areas such as the knee, shoulder, hip, or ankle. The skin is cleaned and numbed with a local anesthetic before the needle is inserted. The procedure takes only a few minutes and most patients feel little more than a pinch. Relief may begin within a few days and can last weeks to months. Imaging guidance such as ultrasound or fluoroscopy is sometimes used for accuracy.

Joint pain refers to discomfort, aching, or soreness in any of the body's joints, such as the knees, hips, shoulders, elbows, or wrists. The pain may be mild or severe, short-lived or long-lasting. Common causes include osteoarthritis, rheumatoid arthritis, gout, bursitis, injury, or infection. Joints may also feel swollen, stiff, warm, or red. Rest, ice, over-the-counter anti-inflammatories, and gentle exercise can help mild cases. See a provider if the joint is very swollen or hot, the pain follows an injury, limits your daily activities, or does not improve within a few days.

ICD-10: M25

Joint swelling refers to visible or palpable enlargement of one or more joints, often accompanied by warmth, redness, and pain. It occurs when fluid accumulates inside the joint or surrounding tissues become inflamed. Common causes include osteoarthritis, rheumatoid arthritis, gout, bursitis, injury or trauma, and infections such as septic arthritis. Sudden swelling of a single joint, especially with intense pain and fever, may indicate infection or gout and requires prompt evaluation. Chronic joint swelling affecting multiple joints often points to an inflammatory or autoimmune condition. Blood tests, joint fluid analysis, and imaging help determine the cause.

ICD-10: M25

The jugular veins are large veins on each side of your neck that carry blood from the head and brain back to the heart. There are two main jugular veins on each side: the internal jugular, which drains blood from the brain, and the external jugular, which is visible under the skin and drains blood from the outer parts of the head and face. Doctors examine the jugular veins during a physical exam. Distended (bulging) jugular veins can signal heart failure or increased pressure in the chest. The internal jugular vein is often used by doctors to place a central line — a special catheter inserted into a large vein for delivering medications, fluids, or measuring blood pressure in seriously ill patients.

The kidneys are two bean-shaped organs, each about the size of a fist, located on either side of your spine just below your rib cage. Their main job is to filter your blood, removing waste products and excess fluid that become urine. They also regulate blood pressure, control the balance of electrolytes like sodium and potassium, and produce a hormone that tells the body to make red blood cells. Common kidney problems include kidney stones, infections, and chronic kidney disease. Blood and urine tests are used to check how well your kidneys are working. Your doctor may order an ultrasound or CT scan to look at the kidneys.

Kidney cancer, most commonly renal cell carcinoma, is a malignant tumor that starts in the kidneys. Early-stage kidney cancer often causes no symptoms, and many cases are discovered incidentally during imaging for other conditions. When symptoms do occur, they may include blood in the urine, back or side pain, or a palpable mass. Risk factors include smoking, obesity, high blood pressure, and family history. Treatment options include surgery (partial or radical nephrectomy), targeted therapy, immunotherapy, and sometimes radiation. Prognosis is generally better when caught early.

ICD-10: C64

Kidney stones are hard deposits made of minerals and salts that form inside the kidneys. They develop when urine becomes too concentrated, allowing minerals to crystallize and stick together. Small stones often pass on their own through the urinary tract, causing intense pain as they move. Symptoms include severe pain in the side and back, pain radiating to the lower abdomen and groin, painful urination, blood in the urine, nausea, and vomiting. Risk factors include dehydration, certain diets, obesity, and family history. Treatment depends on stone size and includes increased fluid intake, pain medications, and procedures such as shock wave therapy or ureteroscopy for larger stones.

ICD-10: N20

Knee pain is any ache, soreness, or discomfort in or around the knee joint. It can result from injury, overuse, or underlying conditions such as arthritis, bursitis, or tendinitis. The knee may also swell, feel stiff, or make popping sounds. Pain may be felt at the front, side, or back of the knee. Common injuries include ligament tears (such as the ACL), meniscus tears, and fractures. Rest, ice, compression, and elevation (RICE) help many mild cases. See a provider if the knee is very swollen, cannot bear weight, feels unstable or locked, or if the pain follows a significant injury.

ICD-10: M25

Knee replacement surgery removes damaged cartilage and bone from the knee joint and replaces them with artificial components made of metal and plastic. It is performed to relieve severe knee pain and stiffness caused by arthritis or injury when other treatments such as medication and physical therapy no longer provide relief. The surgery is performed under general or regional anesthesia and takes one to two hours. A hospital stay of one to three days is typical. Physical therapy begins the day after surgery and continues for weeks to months. Most patients return to daily activities within six weeks and experience lasting pain relief and improved mobility.

Kyphosis is an exaggerated forward rounding of the upper back, commonly called a hunchback or hump. A small degree of rounding is normal, but pronounced kyphosis causes a noticeable curve that can lead to back pain, stiffness, and fatigue. In older adults it is often linked to osteoporosis and vertebral compression fractures. In adolescents, Scheuermann's kyphosis involves structural wedge-shaped vertebrae. Poor posture can cause flexible kyphosis in younger people. Treatment ranges from physical therapy and posture exercises to bracing in adolescents, and surgery when the curve is severe or progressive and causing neurological symptoms.

ICD-10: M40

Labor induction is a medical process to start labor artificially before it begins on its own. It is recommended when continuing the pregnancy poses more risk than delivering — for example, if you are past 41 weeks, have preeclampsia, or your baby is not growing well. Methods include medications (such as Pitocin or prostaglandin gel to ripen the cervix) and mechanical techniques like a balloon catheter or breaking your water. Induction can take hours or even days. Your care team will monitor you and your baby continuously during the process. Not all inductions lead to vaginal delivery.

ICD-10: O61

A lactation consultant is a healthcare professional — often certified as an IBCLC (International Board Certified Lactation Consultant) — who specializes in breastfeeding support. They help with latch problems, low milk supply, engorgement, nipple pain, and pumping. You can see a lactation consultant in the hospital right after birth, through your OB or midwife's practice, or at a community clinic. Most insurance plans cover lactation counseling under the Affordable Care Act preventive care benefit. A lactation consultant can also help if you are using a breast pump or supplementing with formula.

A laminectomy is surgery that removes part or all of the lamina, the back portion of a vertebra, to relieve pressure on the spinal cord or nerve roots. It is commonly performed for spinal stenosis, a condition in which the spinal canal narrows and compresses nerves, causing pain, numbness, or weakness in the legs. The procedure is done under general anesthesia and takes one to three hours. A hospital stay of one to three days is typical. Most patients notice improvement in leg symptoms soon after surgery. Recovery involves avoiding heavy lifting for several weeks, and physical therapy is often recommended to strengthen back muscles and prevent future problems.

The larynx, commonly called the voice box, is a hollow, cartilage-lined structure in the front of your neck that connects the pharynx (throat) to the trachea (windpipe). It serves two vital functions: protecting your airway when you swallow by closing a flap called the epiglottis, and producing sound for speech. The vocal cords are housed inside the larynx. When air passes through the larynx, the vocal cords vibrate to create sound, which is then shaped into words by your tongue, lips, and teeth. Conditions affecting the larynx include laryngitis (inflammation), polyps, nodules, or cancer. Throat cancer often begins in the larynx. A laryngoscopy is an exam that lets doctors look directly at the larynx.

Laser therapy uses focused beams of light energy to treat a variety of medical and dermatological conditions. In medicine, lasers can destroy abnormal tissue, seal blood vessels, remove lesions, treat diabetic retinopathy, address skin conditions like port-wine stains or acne scarring, and provide pain relief for musculoskeletal injuries. The type of laser and its wavelength are selected based on the target tissue and condition. Treatments may be done in a clinic or surgical suite, and some applications require local anesthesia or topical numbing cream. Sessions are usually brief, and results develop gradually over days to weeks.

Laxatives are medications used to relieve constipation by promoting bowel movements. There are several types: bulk-forming laxatives (like psyllium) add fiber; osmotic laxatives (like polyethylene glycol) draw water into the colon; stimulant laxatives (like bisacodyl) trigger muscle contractions; and stool softeners (like docusate) make stool easier to pass. Drinking plenty of water is essential when taking laxatives. Most are for short-term use — chronic use of stimulant laxatives can lead to dependence and loss of normal bowel function. If constipation is persistent or painful, see a doctor, as it can sometimes signal an underlying condition.

Leg swelling (edema) is a buildup of fluid in the tissues of the lower legs. It may affect one or both legs and range from mild puffiness to severe swelling. Common causes include prolonged sitting or standing, a sedentary lifestyle, pregnancy, high salt intake, and medications such as calcium channel blockers. More serious causes include heart failure, kidney disease, liver disease, blood clots (deep vein thrombosis), and venous insufficiency. Sudden swelling in one leg — especially with pain, warmth, or redness — may indicate a blood clot; go to the ER promptly. Bilateral swelling with shortness of breath may signal heart failure. Elevating legs and reducing salt may ease mild cases.

ICD-10: R60

The lens of the eye is a clear, flexible, oval structure located just behind the iris and pupil. Its main job is to focus light precisely onto the retina at the back of the eye. Unlike the cornea, the lens can change shape — flattening or thickening — to focus on objects at different distances. This process is called accommodation. The lens is held in place by fine fibers attached to a ring of muscle. With age, the lens gradually becomes stiffer, making it harder to focus on near objects, a condition called presbyopia. When the lens becomes cloudy, it is called a cataract, which blurs and dims vision. Cataract surgery removes the clouded lens and replaces it with a clear artificial lens implant.

Lethargy is a state of extreme tiredness, drowsiness, and reduced alertness that goes beyond normal fatigue. A person who is lethargic may be hard to rouse, respond slowly, and lack the usual energy or interest in surroundings. In infants and young children, lethargy is always a serious warning sign requiring immediate evaluation. In adults, causes include severe infections, head injury, stroke, metabolic disorders, thyroid problems, medication effects, and overdose. Sudden-onset lethargy, especially with fever or confusion, is a medical emergency. Always seek prompt medical attention if someone appears significantly more drowsy or unresponsive than usual.

ICD-10: R53

A letter of medical necessity is a document written by your physician explaining why a specific treatment, medication, device, or service is medically required for your condition. Insurers often require this letter before approving coverage for services that might otherwise be considered experimental, cosmetic, or not automatically covered under your plan. The letter typically includes your diagnosis, treatment history, the proposed treatment, and why alternatives are insufficient. It is commonly requested for durable medical equipment, off-label drug use, certain therapies, or step therapy exceptions. A strong letter from your doctor significantly improves approval chances.

Leukemia is a cancer of the blood and bone marrow that causes the body to produce abnormal white blood cells. These cells crowd out healthy blood cells, leading to fatigue, frequent infections, easy bruising, and bleeding. Leukemia can be acute (fast-growing) or chronic (slow-growing), and is classified by the type of white blood cell affected. Treatment depends on the type and may include chemotherapy, targeted therapy, immunotherapy, or stem cell transplant. Children with leukemia often respond very well to treatment. Early diagnosis improves outcomes significantly.

ICD-10: C91

Level of care refers to the intensity and type of medical or behavioral health services a patient needs, ranging from primary preventive care to emergency or intensive care. Insurance plans use level-of-care criteria — often based on clinical guidelines — to determine whether the setting and intensity of treatment is medically appropriate and eligible for coverage. Common levels include outpatient, intensive outpatient, partial hospitalization, and inpatient. If an insurer determines care is at a higher or lower level than necessary, it may deny part of the claim. Utilization review teams assess level of care during prior authorization and concurrent review.

In healthcare, a lien is a legal claim placed against your personal injury settlement, lawsuit proceeds, or estate to recover medical costs paid on your behalf. A Medicaid lien allows the state to seek reimbursement for Medicaid-covered care from your estate after death or from a personal injury settlement you receive. Hospitals and health insurers may file similar liens against injury settlements. Federal law limits certain Medicaid estate recovery practices—for instance, protecting a primary residence during a surviving spouse's lifetime in many states. If you receive a personal injury settlement, consult an attorney familiar with healthcare liens to negotiate or satisfy any outstanding claims before keeping the remaining funds.

A life-changing event (LCE) is a significant personal or financial occurrence—such as retirement, divorce, death of a spouse, marriage, loss of income-producing property, or loss of employer pension income—that qualifies you to ask Medicare to recalculate your IRMAA surcharge based on a more recent tax year. You report the event to Social Security using Form SSA-44 with supporting documentation such as a retirement letter or divorce decree. For ACA marketplace plans, many of these same events—plus loss of employer coverage or gaining a new dependent—open a 60-day Special Enrollment Period outside the standard annual open enrollment window, letting you enroll in or change coverage.

Ligaments are strong bands of fibrous tissue that connect bones to other bones at a joint, holding the skeleton together and keeping joints stable. Unlike tendons, which attach muscle to bone, ligaments connect bone to bone. Common ligaments include the ACL (anterior cruciate ligament) and MCL in the knee, and the ligaments of the ankle. Ligaments are somewhat flexible but do not stretch easily. When they are forced beyond their limits, they can become sprained or torn. A complete ligament tear may require surgery and weeks to months of rehabilitation. Ligament damage often causes pain, swelling, and joint instability.

Limb weakness refers to reduced strength in one or more arms or legs, making it hard to lift objects, grip, walk, or climb stairs. It may come on gradually — suggesting nerve compression, vitamin deficiency, or chronic disease — or suddenly, suggesting stroke or spinal injury. Sudden weakness on one side of the body is a classic stroke warning sign — call 911 immediately. Even weakness that resolves within minutes (transient ischemic attack) requires urgent evaluation. Other causes include multiple sclerosis, Guillain-Barré syndrome, peripheral neuropathy, and electrolyte imbalances. Mild weakness that improves with movement should still be reported to a healthcare provider.

ICD-10: G83

A lipid panel measures the levels of fats (lipids) in your blood to assess your risk for heart disease and stroke. It reports total cholesterol, LDL (bad) cholesterol, HDL (good) cholesterol, and triglycerides. Blood is drawn from a vein in your arm, usually after fasting for nine to twelve hours so food does not temporarily raise your triglyceride level. High LDL and triglycerides combined with low HDL increase the risk of plaque building up in arteries. Your doctor uses the results alongside your blood pressure, weight, age, and smoking history to guide decisions about diet, exercise, or cholesterol-lowering medications.

A liquid medication is a drug in fluid form, such as a syrup, solution, suspension, or elixir, that is swallowed or administered through a feeding tube. Liquids are often prescribed for children, elderly patients, or anyone who has difficulty swallowing solid tablets or capsules. Some liquid medications, especially suspensions, must be shaken vigorously before each dose to distribute the drug evenly throughout the liquid. Measure doses precisely using the oral syringe or dosing cup provided by the pharmacy, never a regular kitchen spoon, since household spoon sizes vary and can lead to incorrect dosing. Store liquids as directed, as some require refrigeration to remain effective.

The liver is the largest internal organ, weighing about three pounds and sitting in the upper right part of the abdomen under the rib cage. It performs more than 500 functions essential to life. It filters the blood coming from the digestive tract, removing toxins, drugs, and waste products. It produces bile to help digest fats, manufactures most of the proteins in the blood including those that help it clot, and stores glucose as glycogen to regulate blood sugar. The liver also processes medications, which is why drug dosing can be affected by liver disease. Common liver conditions include hepatitis — inflammation of the liver — cirrhosis — scarring from long-term damage — and fatty liver disease.

Liver function tests (LFTs) are a group of blood tests that measure proteins and enzymes made by the liver or released when liver cells are damaged. Common markers include ALT, AST, ALP, bilirubin, total protein, and albumin. Elevated levels can indicate hepatitis, fatty liver disease, bile duct blockage, or medication side effects. Blood is drawn from a vein in your arm; fasting is sometimes requested but not always required. Results help doctors determine whether the liver is inflamed, injured, or failing to produce essential proteins. LFTs are often ordered as part of a comprehensive metabolic panel or during routine monitoring of patients on long-term medications.

A loading dose is a larger-than-usual initial dose given at the start of treatment to quickly bring a drug to a therapeutic level in your body. After the loading dose, smaller regular maintenance doses keep the drug at that effective concentration. Loading doses are used for medications that take a long time to accumulate in the body, such as certain heart rhythm drugs, blood thinners, and some antibiotics, when rapid treatment is necessary. Your provider will explain if a loading dose is part of your plan. Do not skip or modify a loading dose without guidance, as doing so can delay your treatment response.

Local anesthesia is medication injected or applied directly to a small area of the body to numb it and block pain signals during a minor procedure. The patient remains fully awake and alert. It is used for procedures such as biopsies, minor skin surgeries, dental work, stitching of wounds, cataract surgery, and some injections. Common local anesthetics include lidocaine and bupivacaine. The injection may sting briefly before the numbness sets in. The numbing effect lasts from 30 minutes to several hours depending on the agent used. After it wears off, some soreness at the injection site is normal. Local anesthesia is generally very safe with minimal side effects and is preferred when general anesthesia is not necessary.

Long-term care (LTC) refers to services that help people with chronic illness, disability, or cognitive decline—such as Alzheimer's disease—perform daily activities like bathing, dressing, and eating over months or years. Services may be delivered at home, in adult day programs, assisted living facilities, or skilled nursing facilities. Medicare covers limited skilled nursing facility stays after a qualifying hospital admission but does not cover ongoing custodial care. Medicaid pays for long-term care—including nursing home costs—for people who meet income and asset eligibility requirements. Private long-term care insurance is another funding option. Planning ahead matters because these services can be very expensive.

Loss of appetite, medically called anorexia, means a reduced desire to eat. It is different from the eating disorder anorexia nervosa. Short-term loss of appetite commonly accompanies viral illness, nausea, or emotional stress and usually resolves on its own. Persistent loss of appetite lasting more than a week, or accompanied by unintentional weight loss, fatigue, or other symptoms, can signal conditions such as chronic infection, liver disease, kidney disease, thyroid disorders, depression, or cancer. Any significant or unexplained loss of appetite lasting more than one to two weeks should be discussed with a healthcare provider.

ICD-10: R63

Loss of consciousness means becoming unresponsive and unaware of your surroundings, either briefly (fainting) or for a longer period. Brief episodes are often caused by low blood pressure, low blood sugar, emotional stress, or dehydration. More serious causes include cardiac arrhythmias, stroke, head injury, seizure, and drug overdose. Call 911 immediately if someone loses consciousness and does not regain it within a minute, stops breathing, has a seizure, or if the event follows a head injury, chest pain, or rapid heartbeat. Never leave an unconscious person alone. Place them on their side if they are breathing to protect the airway.

ICD-10: R55

Loss of coverage occurs when you involuntarily lose your health insurance—because you lost a job, aged off a parent's plan at 26, your COBRA expired, your employer stopped offering benefits, or your Medicaid or CHIP eligibility ended. Losing coverage qualifies you for a Special Enrollment Period on the ACA marketplace, generally giving you 60 days before or after coverage ends to enroll in a new plan. You may also elect COBRA to continue your former employer's coverage for up to 18 months by paying the full premium plus an administrative fee. Acting quickly prevents gaps in coverage that could leave you financially exposed to unexpected medical costs.

A Limited Purpose Flexible Spending Account (LPFSA) is a pre-tax spending account restricted to qualified dental and vision expenses only, designed to be used alongside a Health Savings Account (HSA). IRS rules generally prohibit having both a standard healthcare FSA and an HSA simultaneously, so the LPFSA solves this by limiting its scope to dental and vision costs. This lets you pay for orthodontics, cleanings, contact lenses, and prescription eyeglasses with pre-tax dollars while preserving your HSA funds for general medical expenses or long-term savings. LPFSA contributions are typically use-it-or-lose-it each plan year, though many employers allow a small rollover or brief grace period.

A lumbar puncture, commonly called a spinal tap, is a procedure in which a doctor inserts a thin needle between two lower vertebrae to collect a small amount of cerebrospinal fluid (CSF) — the liquid that surrounds and protects the brain and spinal cord. You will lie on your side or sit leaning forward while the area is numbed with local anesthetic. The fluid is analyzed for signs of meningitis, encephalitis, multiple sclerosis, certain cancers, and other neurological conditions. The procedure takes about 30–45 minutes. Afterward you may experience a headache, which is treated by lying flat and drinking fluids. Results typically take one to three days.

The lumbar vertebrae are the five large bones that make up the lower portion of your spine, labeled L1 through L5. They are located in your lower back, between the chest and the pelvis. Because they support most of your body weight and allow movement like bending and twisting, they are subject to a lot of stress. The lumbar region is a very common source of back pain. Conditions affecting this area include herniated discs, spinal stenosis, and compression fractures. Sciatica — pain that radiates down the leg — often originates from nerves in the lumbar spine being compressed or irritated.

A lump or mass is an abnormal swelling or growth that can appear anywhere in or on the body. Many lumps are harmless, such as cysts, lipomas, or enlarged lymph nodes from infection. However, a new or changing lump should always be evaluated by a doctor to rule out cancer or other serious conditions. Features that raise concern include rapid growth, hard or fixed consistency, irregular borders, skin changes overlying the lump, or associated symptoms such as pain, fever, or weight loss. Imaging, blood tests, and biopsy may be needed to make a definitive diagnosis and guide appropriate treatment.

Lung cancer is a malignant tumor that starts in the lungs and is one of the leading causes of cancer death in the United States. The two main types are non-small cell lung cancer and small cell lung cancer. The most common cause is cigarette smoking, but it can also occur in non-smokers due to radon gas, asbestos, or air pollution exposure. Symptoms include persistent cough, coughing up blood, chest pain, hoarseness, unintentional weight loss, and shortness of breath. Treatment depends on type and stage and may include surgery, chemotherapy, radiation, targeted therapy, or immunotherapy. Annual low-dose CT screening is recommended for high-risk individuals.

ICD-10: C34

Lupus is a chronic autoimmune disease where the immune system attacks healthy tissue throughout the body, causing widespread inflammation. It can affect the skin, joints, kidneys, brain, lungs, and heart. The classic butterfly-shaped rash across the cheeks and nose is a recognizable sign. Symptoms flare and remit unpredictably and include fatigue, joint pain, fever, and sensitivity to sunlight. Lupus is far more common in women, particularly of African, Hispanic, and Asian descent. Treatment involves anti-inflammatory medications, immunosuppressants, and hydroxychloroquine to reduce flares.

ICD-10: M32

Lyme disease is caused by the bacterium Borrelia burgdorferi and is transmitted to humans through the bite of infected black-legged ticks. Early symptoms include a characteristic bull's-eye rash called erythema migrans, fever, chills, fatigue, headache, and muscle and joint aches. If untreated, the infection can spread to the joints, heart, and nervous system. Diagnosis is made clinically and confirmed with blood tests. Treatment with antibiotics such as doxycycline for two to four weeks is usually effective when started early. Some people experience lingering symptoms after treatment called post-treatment Lyme disease syndrome. Preventing tick bites with repellent and checking for ticks after outdoor activities reduces risk.

ICD-10: A69

Lymph nodes are small, bean-shaped structures that are part of the body's immune system. They act as filters, trapping bacteria, viruses, and cancer cells that travel through the lymphatic vessels. Dozens of lymph nodes are found throughout the body, including in the neck, armpits, and groin. In the head and neck region, lymph nodes are grouped in clusters around the jaw, under the chin, along the sides of the neck, and at the base of the skull. When you have an infection, nearby lymph nodes often become swollen and tender — this is a sign the immune system is working. Persistently enlarged lymph nodes may indicate chronic infection, autoimmune disease, or lymphoma (cancer of the lymphatic system) and should be evaluated by a doctor.

Lymph node dissection is a surgical procedure to remove lymph nodes from a region of the body to check whether cancer has spread. It is commonly performed alongside cancer surgeries such as mastectomy, melanoma excision, or colorectal surgery. The removed nodes are sent to a laboratory for examination. Sentinel lymph node biopsy, a less extensive approach, removes only the first one to three lymph nodes that drain from the tumor. A full axillary or regional dissection removes more nodes. Risks include lymphedema, a condition causing persistent swelling, numbness, or tightness in the nearby limb. Recovery depends on the extent of surgery and the primary procedure performed alongside it.

Lymph nodes are small glands found in the neck, armpits, and groin that help fight infection. When they swell, it is usually because your body is fighting a nearby infection such as a cold, ear infection, or strep throat, and they return to normal size once the infection resolves. Persistent swelling lasting more than two to four weeks, nodes that are hard, fixed, or painless, or swollen nodes in multiple areas of the body may indicate a more serious condition such as lymphoma, leukemia, or another infection requiring evaluation. See your doctor for proper assessment.

ICD-10: R59

Lymphocytes are a type of white blood cell that plays a central role in your immune system. There are two main types: B cells, which produce antibodies to fight bacteria and viruses, and T cells, which directly attack infected or cancerous cells. Lymphocytes circulate through the blood and lymphatic system and are found in high numbers in lymph nodes and the spleen. A low lymphocyte count (lymphocytopenia) can result from certain infections like HIV, autoimmune diseases, or chemotherapy, and can leave you more vulnerable to illness. A high count (lymphocytosis) may indicate a viral infection or certain blood cancers like chronic lymphocytic leukemia (CLL). Lymphocytes are measured as part of a complete blood count.

Lymphoma is a cancer of the lymphatic system, which is part of the body's immune system. There are two main types: Hodgkin lymphoma and non-Hodgkin lymphoma. Symptoms often include swollen lymph nodes in the neck, armpits, or groin; fatigue; unexplained weight loss; fever; and night sweats. Hodgkin lymphoma is highly treatable and often curable. Non-Hodgkin lymphoma is more varied in behavior and treatment. Treatment may include chemotherapy, radiation, immunotherapy, or stem cell transplant depending on the type and stage.

ICD-10: C85

Macular degeneration is a disease that damages the macula, the central part of the retina responsible for sharp, detailed vision. It is the leading cause of severe vision loss in people over 50 in the US. There are two types: dry (more common, slower progression) and wet (less common, faster and more severe). Symptoms include blurry central vision, distorted lines, and difficulty reading or recognizing faces. Risk factors include age, smoking, and family history. While there is no cure, treatments like anti-VEGF injections can slow progression of wet AMD.

ICD-10: H35

MAGI—Modified Adjusted Gross Income—is the income measure used by the federal government to determine eligibility for ACA marketplace subsidies, Medicaid, and CHIP. It begins with your Adjusted Gross Income (AGI) from your federal tax return and adds back non-taxable Social Security benefits, tax-exempt interest, and certain excluded foreign income. Unlike older asset-based Medicaid rules, MAGI does not count savings accounts, a home, or other property—only income flows. Your household MAGI as a percentage of the Federal Poverty Level sets your subsidy amount or Medicaid eligibility tier. Underestimating your MAGI when applying for tax credits can create a repayment obligation at tax time.

A mail-order pharmacy is a licensed pharmacy that ships your medications directly to your home or another address, eliminating the need to visit a physical store. Many insurance plans encourage or require mail-order for maintenance medications because they offer lower copays, often for a 90-day supply compared to a 30-day retail supply. Mail-order is convenient for people who take regular long-term medications and cannot make monthly pharmacy trips. Allow several business days for your prescription to arrive. Verify that your current address is on file and arrange to receive medications that require refrigeration or signature upon delivery so they are not left unattended outside.

A maintenance drug is a prescription medication taken regularly on a long-term basis to manage a chronic condition such as diabetes, hypertension, asthma, or depression. Because patients refill these medications repeatedly, many insurance plans offer discounts—sometimes waiving one month's copay—when you obtain a 90-day supply through a mail-order pharmacy instead of monthly retail refills. Maintenance drugs are typically listed on a plan's formulary at preferred generic or brand tiers. Some plans require step therapy, meaning you must try a generic before the plan covers a brand-name maintenance drug. Checking that your maintenance drugs remain on your new plan's formulary before switching coverage helps prevent unexpected cost surprises.

A maintenance medication is a drug you take on a regular, ongoing basis to manage a chronic condition such as high blood pressure, diabetes, asthma, high cholesterol, or depression. Unlike medications taken only when symptoms flare up, maintenance medications keep your condition stable over time. Missing doses or stopping abruptly can cause your condition to worsen or produce withdrawal effects. Many insurance plans offer lower copays or mail-order discounts for maintenance medications because they are long-term. Your doctor will monitor you periodically to ensure the medication remains effective and that the dose is still appropriate for your needs.

Malaise is a vague feeling of discomfort, illness, or not feeling well that is difficult to describe. It is a nonspecific symptom often associated with many medical conditions. Patients may describe it as feeling run-down, off, or just not right. Malaise commonly accompanies infections, inflammatory diseases, autoimmune conditions, metabolic disorders, anemia, depression, and cancer. It is also an early sign of many acute illnesses. While malaise alone is not diagnostic, persistent or worsening malaise, especially combined with other symptoms such as fever, weight loss, or fatigue, warrants evaluation to identify an underlying cause.

ICD-10: R53

A mammogram is an X-ray of the breast used to screen for or diagnose breast cancer and other abnormalities. Each breast is placed on a flat support plate and compressed briefly by a plastic paddle to spread out the tissue for clearer images. The compression lasts only a few seconds but may cause temporary discomfort or mild pain, especially around the time of your menstrual period. The test usually takes about 20 minutes. You should avoid using deodorant, powder, or lotion under your arms or on your breasts on the day of the exam, as these can appear on the images. Annual screening mammograms are generally recommended beginning at age 40 or 45 depending on your risk factors.

A Managed Care Organization (MCO) is a health plan or entity that coordinates and delivers medical services through a contracted provider network, using tools such as prior authorization, care management, utilization review, and referral requirements to control costs and improve quality. Many state Medicaid programs contract with MCOs to administer benefits for enrolled members. MCOs operate under various models—HMOs require a primary care gatekeeper, PPOs allow more flexibility. Members typically receive a member handbook, a provider directory, and a benefits summary specific to their MCO. If you are enrolled in Medicaid through an MCO, your benefits are administered by that organization rather than directly by the state.

A mastectomy is surgery to remove one or both breasts, partially or completely. It is most commonly performed to treat or prevent breast cancer. Types include total mastectomy, which removes the entire breast, and skin-sparing or nipple-sparing approaches that may allow for immediate reconstruction. Lymph nodes may also be removed to check for cancer spread. The surgery is done under general anesthesia and typically takes two to three hours. Hospital stay is one to two days. Drainage tubes placed during surgery are removed after several days at a follow-up visit. Many women choose breast reconstruction, which can be started at the time of mastectomy. Full recovery takes four to six weeks.

A mechanical ventilator is a machine that assists or replaces a patient's breathing by pushing air (with or without added oxygen) into the lungs through an endotracheal tube or a mask. It is used when a patient cannot breathe adequately on their own due to respiratory failure, severe illness, surgery, or injury. The ventilator is programmed by respiratory therapists and physicians to match the patient's needs. Patients on ventilators in the ICU are closely monitored. Being on a ventilator is serious and often indicates critical illness. The goal is usually to wean the patient off the machine as soon as safely possible.

Medicaid is a joint federal-state health insurance program that provides coverage to low-income individuals and families, including children, pregnant women, elderly adults, and people with disabilities. Eligibility and benefits vary by state. The ACA expanded Medicaid eligibility in participating states to cover adults up to 138% of the federal poverty level. Medicaid is generally free or very low-cost for enrollees. It is administered by state agencies and may go by different names in different states.

Medicaid Expansion refers to the ACA provision allowing states to extend Medicaid to most adults under 65 with incomes up to 138 percent of the Federal Poverty Level, regardless of disability or family structure. Before expansion, many states only covered parents, children, pregnant women, the elderly, and people with disabilities who met strict categorical criteria. States that adopted expansion receive enhanced federal matching funds. As of 2025, most states have expanded. Adults in expansion states who would otherwise be uninsured can enroll in Medicaid at any time they become eligible—there is no limited enrollment window for Medicaid, unlike marketplace plans.

Medicaid Expansion CHIP refers to Children's Health Insurance Program coverage provided under Medicaid expansion rules in states that adopted the ACA expansion. CHIP gives low-cost coverage to children in families that earn too much for regular Medicaid but cannot afford private insurance. Some states extend CHIP-funded coverage to pregnant women through perinatal CHIP programs. Families apply through the same application used for Medicaid and marketplace plans, and the system routes the child to the appropriate program. Eligibility income limits vary by state. Covered children receive comprehensive benefits including preventive care, dental, vision, and mental health services at low or no cost.

Medicaid spend-down is a pathway to Medicaid eligibility for individuals whose income exceeds normal limits but who have high medical expenses. By 'spending down' their income on medical bills to below the Medicaid income threshold, they become eligible for coverage. This is similar to a deductible — once the spend-down amount is met, Medicaid covers the remainder. Spend-down programs are available in some but not all states and primarily serve elderly and disabled individuals with high medical costs.

Medical debt is unpaid healthcare bills that a patient owes to a hospital, clinic, or provider. It is the leading cause of personal bankruptcy in the US. Key patient rights regarding medical debt include: the right to an itemized bill, the right to apply for financial assistance before any debt goes to collections, and federal protections limiting how medical debt affects credit scores (credit bureaus began removing medical debt under $500 from reports in 2023). Negotiating with billing departments directly often results in reduced balances.

A medical interpreter is a trained professional who translates spoken or written communication between patients and healthcare providers who do not share the same language. Under US federal law (Title VI of the Civil Rights Act), hospitals that receive federal funding must provide free language services to patients with limited English proficiency. You have the right to a professional medical interpreter for any clinical conversation, including the ER. Interpreters may be present in person, by phone, or by video. Using untrained family members, especially children, for medical interpretation is discouraged. Always ask for a certified medical interpreter if you are not comfortable communicating in English.

Medical interpreter services provide qualified language interpretation for patients with limited English proficiency during healthcare encounters. Under Section 1557 of the ACA, covered healthcare entities must provide free interpreter services — either in-person, by phone, or via video remote interpreting. Professional medical interpreters are trained in clinical terminology and ethics, unlike ad hoc interpreters such as family members or bilingual staff. Major language lines include Language Line Solutions and other telephonic interpretation services available at most hospitals.

Medical necessity is a standard insurers use to determine whether a service, treatment, or supply is appropriate and will be covered. To meet this standard, a service must generally be consistent with accepted medical practice, appropriate to the patient's diagnosis, not primarily for the patient's or provider's convenience, and no more intensive than the condition requires. Insurers compare services against clinical guidelines and evidence-based criteria. Services that do not meet medical necessity standards are denied as not covered. If your claim is denied for this reason, your doctor can provide supporting documentation and you can file an appeal with clinical evidence to challenge the decision.

A Medical Screening Examination (MSE) is the required assessment that hospital emergency departments must perform for every person who presents seeking care, regardless of ability to pay, insurance status, citizenship, or identification. Established under EMTALA—the Emergency Medical Treatment and Labor Act—the MSE must be conducted by a qualified medical professional to determine whether an emergency medical condition exists. If one is found, the hospital must provide stabilizing treatment or arrange an appropriate transfer. Refusing to conduct an MSE or turning a patient away before one is completed is a federal violation that can result in fines and loss of Medicare participation.

Medicare Advantage (Part C) is an alternative to Original Medicare offered by private insurance companies approved and regulated by Medicare. These plans must cover everything Original Medicare covers but frequently add benefits such as dental, vision, hearing, and fitness programs. Most Medicare Advantage plans include prescription drug coverage (Part D). You typically select a network of providers and may need referrals for specialist care. Premiums, network size, and extra benefits vary widely by plan and location. To enroll, you must already have Medicare Parts A and B and live in the plan's service area. You can switch back to Original Medicare during annual enrollment periods if your needs change.

Medicare Part A is hospital insurance provided under the federal Medicare program. It covers inpatient hospital stays, skilled nursing facility care, hospice care, and some home health services. Most people qualify for premium-free Part A at age 65 if they or their spouse worked and paid Medicare taxes for at least 10 years. Part A has deductibles and benefit periods rather than out-of-pocket maximums. Coinsurance applies after extended inpatient stays.

Medicare Part B covers outpatient medical services including doctor visits, preventive care, outpatient surgery, durable medical equipment, and certain laboratory tests. Part B requires a monthly premium (income-adjusted) and has an annual deductible, after which Medicare pays 80% of approved costs and the enrollee pays 20% (with no out-of-pocket cap unless supplemented by Medigap). Late enrollment penalties apply if Part B is not enrolled in promptly when first eligible.

Medicare Part C, or Medicare Advantage, is an alternative to Original Medicare offered by private insurers approved by Medicare. Plans must cover all Part A and B services and often include Part D prescription drug coverage, dental, vision, and hearing benefits. Medicare Advantage plans typically operate as HMOs or PPOs with network restrictions. Monthly premiums may be low or zero, but out-of-pocket costs vary by plan. Enrollment requires simultaneous Part A and B.

Medicare Part D provides prescription drug coverage available as a standalone plan to complement Original Medicare or included in Medicare Advantage plans. Part D plans have their own monthly premiums, deductibles, and formularies. Coverage tiers affect cost: generic drugs in lower tiers are cheapest, while specialty drugs in higher tiers carry higher cost-sharing. A late enrollment penalty applies for those who delay Part D enrollment without other creditable drug coverage.

Medicare Secondary Payer (MSP) rules determine when Medicare pays after another insurer—such as an employer group health plan, workers' compensation, or auto insurance—pays first. If you are actively employed and your employer covers 20 or more employees, your employer's group health plan generally pays first and Medicare pays second. If your employer has fewer than 20 employees or you are retired, Medicare typically pays first. MSP rules protect Medicare from paying costs another insurer should cover. Hospitals and providers must ask patients about other insurance at registration to coordinate benefits correctly. Violating MSP rules can lead to Medicare demanding repayment from providers.

A Medicare Supplement plan, commonly called Medigap, is private health insurance designed to cover the cost-sharing gaps left by Original Medicare (Parts A and B). These gaps include deductibles, coinsurance, and copays that Medicare does not pay. Medigap plans are standardized by the federal government into lettered plan types (A, B, C, D, F, G, K, L, M, N) with consistent benefits regardless of which private insurer sells them. You must already have Medicare Part A and Part B to buy a Medigap policy. Medigap does not cover prescription drugs — you need a separate Part D plan for that.

A medication guide, sometimes called a MedGuide, is an FDA-required written document that pharmacies must give patients when dispensing certain prescription drugs that carry serious risks. Written in plain language for patients, the guide explains the most important information you need, including serious or life-threatening risks, who should not take the drug, how to take it safely, potential side effects to watch for, and what to do if problems occur. Your pharmacist should provide a medication guide each time you receive an applicable prescription. Keep your medication guide and review it if you experience unexpected symptoms or have questions about your treatment.

Medication management is a clinical service in which a physician, pharmacist, or advanced practice provider reviews all of a patient's current medications to ensure they are appropriate, effective, safe, and being used correctly. It is particularly important for patients taking multiple medications, those with chronic conditions, and older adults at risk of drug interactions or side effects. During a medication management visit, the provider may adjust doses, discontinue unnecessary drugs, add new treatments, and educate the patient about proper use and potential interactions. This service helps prevent medication errors and hospitalizations caused by drug-related problems.

Medication reconciliation is the process of carefully comparing the complete list of medications a patient is currently taking against new medication orders or records created during care transitions, such as hospital admission, discharge, or transfer between facilities. The goal is to identify and resolve errors including duplications, omissions, wrong doses, or dangerous interactions. A nurse, pharmacist, or physician will ask you to list every medication you take, including vitamins, supplements, and over-the-counter drugs. Carrying an accurate, up-to-date medication list to every appointment and hospital visit makes this process faster and safer. Medication errors at care transitions are a leading cause of preventable patient harm in the US.

Medication-assisted treatment (MAT) is the use of FDA-approved medications — combined with counseling and behavioral therapies — to treat substance use disorders, particularly opioid use disorder and alcohol use disorder. For opioid use disorder, medications such as buprenorphine (Suboxone), methadone, and naltrexone reduce cravings and withdrawal symptoms and significantly lower the risk of overdose. For alcohol use disorder, medications like naltrexone and acamprosate reduce the urge to drink. MAT is considered a gold-standard, evidence-based treatment and is not simply replacing one drug with another — it is medical care. Most insurance plans are required to cover MAT. SAMHSA's helpline (1-800-662-4357) can help you find MAT providers in your area.

Medigap, also called Medicare Supplement Insurance, is private insurance sold by insurance companies to help pay the gaps in Original Medicare—copays, coinsurance, and deductibles you would otherwise pay out of pocket. Medigap policies are standardized by the federal government and labeled with letters (A, B, D, G, K, L, M, N), meaning each lettered plan type offers identical core benefits regardless of the company selling it. Medigap does not cover prescription drugs—you need a separate Medicare Part D plan. Medigap is designed for beneficiaries on Original Medicare and does not work alongside Medicare Advantage plans. Premiums vary by insurer and location even for the same plan letter.

Medigap Open Enrollment is a one-time, six-month window that starts the month you turn 65 and are enrolled in Medicare Part B. During this period, insurance companies must sell you any Medigap policy they offer in your state at standard rates, regardless of your health history—this is guaranteed issue. After this window closes, insurers in most states can use medical underwriting to deny your application, charge higher premiums, or exclude pre-existing conditions. Some states provide additional consumer protections. If you miss this window, qualifying for Medigap later can be difficult or expensive depending on your health, so enrolling on time is strongly advised.

Melanoma is the most serious type of skin cancer, arising from pigment-producing cells called melanocytes. It can develop anywhere on the body but most commonly appears on areas exposed to the sun. Early detection is critical because melanoma can spread to other organs quickly. Warning signs include changes in an existing mole, or a new growth with irregular borders, multiple colors, or a diameter larger than a pencil eraser. Risk factors include excessive UV exposure and family history. Treatment includes surgery, immunotherapy, and targeted therapy.

ICD-10: C43

Memory loss refers to difficulty recalling recent or past events, learning new information, or recognizing familiar people and places. Short-term memory loss is common with aging, stress, and poor sleep. Causes of significant memory loss include vitamin B12 deficiency, hypothyroidism, depression, medication side effects, alcohol use, stroke, head trauma, and dementia. Sudden memory loss, especially after a head injury or possible stroke, is an emergency — call 911. If memory problems are worsening gradually over weeks or months, schedule a full evaluation with your doctor as soon as possible. Early assessment leads to earlier treatment and better outcomes.

ICD-10: R41

The meninges are three protective layers of tissue that wrap around your brain and spinal cord. Think of them as a cushioning envelope. The outermost layer is tough and called the dura mater. The middle layer, the arachnoid, is thin and web-like. The innermost layer, the pia mater, clings directly to the brain's surface. Between these layers flows cerebrospinal fluid (CSF), a clear liquid that cushions the brain and spinal cord from shocks. Meningitis is an infection or inflammation of these membranes, which is a serious medical emergency. Symptoms include severe headache, stiff neck, and sensitivity to light. Surgery on the brain always involves opening these layers.

Meningitis is inflammation of the membranes, called meninges, surrounding the brain and spinal cord. It is usually caused by a viral or bacterial infection. Bacterial meningitis is the more severe form and can be life-threatening within hours. Symptoms include sudden severe headache, high fever, stiff neck, sensitivity to light, and nausea or vomiting. A rash may appear in bacterial meningitis caused by meningococcal bacteria. Treatment depends on the cause. Bacterial meningitis requires urgent hospitalization and intravenous antibiotics. Viral meningitis usually resolves on its own. Vaccines are available to prevent several types of meningitis including meningococcal and pneumococcal disease.

ICD-10: G03

The meniscus refers to two C-shaped pieces of rubbery cartilage in your knee — the medial meniscus on the inner side and the lateral meniscus on the outer side. They act as shock absorbers between the thigh bone (femur) and the shinbone (tibia), distributing weight evenly across the knee and helping to stabilize the joint. Meniscus tears are one of the most common knee injuries, often caused by twisting the knee while bearing weight. Symptoms include pain, swelling, stiffness, and a clicking or locking sensation. Treatment ranges from rest and physical therapy to arthroscopic surgery, depending on the size and location of the tear.

Mental health parity refers to the legal requirement in the US that insurance plans treat mental health and substance use disorder benefits no less favorably than medical or surgical benefits. The federal Mental Health Parity and Addiction Equity Act (MHPAEA) of 2008 and subsequent regulations prohibit insurers from imposing stricter limits on mental health and addiction care — such as lower visit limits, higher copays, or tighter prior authorization requirements — than those applied to comparable medical benefits. If you believe your insurer is applying more restrictive rules to your mental health benefits than to your medical benefits, you have the right to appeal. Your state insurance commissioner's office and CMS can assist with parity complaints.

The mesentery is a fold of tissue that connects the small intestine and parts of the large intestine to the back wall of the abdomen. Think of it as the attachment structure that anchors the intestines in place and keeps them from tangling. It carries the blood vessels, lymphatic vessels, and nerves that supply the intestines. The mesenteric arteries and veins run through the mesentery to deliver oxygen and carry away blood and nutrients from the bowel. A mesenteric ischemia — reduced blood flow to the intestines through these vessels — is a serious emergency that can cause bowel death. Crohn's disease can also affect the mesentery, causing it to thicken and become inflamed.

Metabolic syndrome is not a single disease but a cluster of conditions that occur together, increasing the risk of heart disease, stroke, and type 2 diabetes. These conditions include high blood pressure, high blood sugar, excess fat around the waist, high triglycerides, and low HDL (good) cholesterol. Having three or more of these factors means a person has metabolic syndrome. It affects about one in three adults in the United States. The underlying drivers are usually excess weight, physical inactivity, and insulin resistance. Treatment focuses on lifestyle changes including weight loss, healthy diet, and regular exercise.

ICD-10: E88

The middle ear is the air-filled space behind the eardrum that transmits sound vibrations from the outer ear to the inner ear. It contains three tiny bones — the malleus (hammer), incus (anvil), and stapes (stirrup) — collectively called the ossicles. These bones form a mechanical chain that amplifies sound vibrations and transfers them to the cochlea in the inner ear. The middle ear is connected to the back of the throat by the Eustachian tube, which equalizes air pressure on both sides of the eardrum. Middle ear infections (otitis media) are very common, especially in children, and occur when bacteria or viruses enter this space and cause fluid buildup and inflammation. Chronic infections can damage the ossicles and cause hearing loss.

A migraine is a type of intense, recurring headache usually felt as a throbbing or pulsating pain on one side of the head, though it can affect both sides. Migraines often last four to 72 hours and can be severely disabling. They are frequently accompanied by nausea, vomiting, and extreme sensitivity to light and sound. Some people experience an aura—visual disturbances like flashing lights or blind spots—before the headache begins. Triggers include stress, hormonal changes, certain foods and drinks, sleep disruption, and strong sensory stimuli. Treatment includes prescription and over-the-counter medications. Managing triggers and following a preventive plan with your provider can reduce how often migraines occur.

ICD-10: G43

Migraine is a neurological condition causing intense, often one-sided throbbing headaches that can last from hours to days. It commonly includes nausea, vomiting, and extreme sensitivity to light and sound. Some people experience an aura—visual disturbances, numbness, or speech changes—before the headache begins. Migraines can be triggered by stress, hormonal changes, certain foods, sleep disruption, or bright lights. They are significantly more common in women. Treatment includes acute medications to stop attacks and preventive medications or lifestyle changes to reduce their frequency and severity.

ICD-10: G43

Mindfulness-based therapy refers to structured therapeutic approaches that incorporate mindfulness practice — intentionally paying attention to the present moment without judgment — to improve mental health. The most established approaches include Mindfulness-Based Cognitive Therapy (MBCT) for preventing depression relapse and Mindfulness-Based Stress Reduction (MBSR) for stress, anxiety, and chronic pain. These programs are typically delivered in group format over eight weeks. Mindfulness is also a core component of DBT and Acceptance and Commitment Therapy (ACT). Research shows mindfulness-based approaches are effective for depression, anxiety, and stress-related conditions. Many hospital systems, community mental health centers, and outpatient programs in the US offer these evidence-based group programs.

The mitral valve is a one-way door inside the heart that separates the left atrium — the upper left chamber — from the left ventricle — the lower left chamber. It has two leaflets, or flaps, that open to let blood flow from the atrium into the ventricle and then snap shut to prevent blood from leaking backward when the ventricle pumps. If the valve does not close tightly, blood leaks back — a condition called mitral regurgitation. If the valve becomes stiff and narrow and does not open fully, less blood gets through — a condition called mitral stenosis. Doctors hear these problems as a heart murmur through a stethoscope and confirm them with an echocardiogram.

A Mobile Crisis Team is a community-based mental health service that dispatches trained clinicians—social workers, counselors, or peer support specialists—directly to a person experiencing a mental health or substance use crisis, often as an alternative or complement to law enforcement response. Teams typically respond through 988 (the Suicide and Crisis Lifeline) or local crisis lines. They assess the situation, de-escalate, and connect the person to treatment or community resources, helping avoid unnecessary emergency room visits or police involvement. Federal Medicaid funding now supports mobile crisis services in many states. Calling 988 first can often get a crisis team to your location faster than calling 911.

Modified Adjusted Gross Income (MAGI) is the income figure the federal government uses to determine eligibility for ACA marketplace subsidies, Medicaid, and CHIP. It starts with your Adjusted Gross Income (AGI) from IRS Form 1040 and adds back non-taxable Social Security benefits, tax-exempt interest income, and excluded foreign-earned income. MAGI does not count assets, savings, or property—only income flows. Your household MAGI as a percentage of the Federal Poverty Level determines your subsidy amount or Medicaid eligibility tier. Calculating MAGI incorrectly when applying for coverage can lead to a wrong tax credit amount and a potential repayment obligation when you file your taxes.

Monoclonal antibodies are laboratory-made proteins designed to mimic the immune system's ability to target specific substances in the body. They are used to treat a wide range of conditions including cancer, autoimmune diseases, asthma, migraines, and infections. Examples include trastuzumab (Herceptin) for breast cancer, adalimumab (Humira) for rheumatoid arthritis, and dupilumab (Dupixent) for eczema. They are usually given as injections or infusions. Drug names ending in "-mab" are typically monoclonal antibodies. Infusion reactions are possible — you may be monitored for a period after administration. These are typically specialty medications and may require prior authorization from insurance.

Mood changes refer to noticeable shifts in emotional state, such as swinging between sadness and happiness, feeling unusually low or high, increased anxiety, or emotional reactions that seem out of proportion to situations. They can be temporary responses to life events or may indicate an underlying condition. Medical causes include thyroid disorders, hormonal imbalances, depression, bipolar disorder, anxiety disorders, premenstrual dysphoric disorder, and neurological conditions. Substance use and certain medications can also affect mood. Discuss persistent or disruptive mood changes with a doctor or mental health professional, as effective treatments including therapy and medication are available.

Morning sickness refers to nausea and vomiting that are common during pregnancy, especially in the first trimester. Despite the name, symptoms can occur at any time of day. It is triggered by rising levels of pregnancy hormones and affects up to 80% of pregnant people. Mild morning sickness is considered normal and usually resolves by weeks 12 to 16. Eating small, frequent meals and staying hydrated can help. A severe form called hyperemesis gravidarum causes intense vomiting and dehydration requiring medical treatment. Contact your provider if you cannot keep fluids down or are losing weight.

ICD-10: O21

An MRA uses magnetic resonance imaging technology to produce detailed pictures of blood vessels throughout the body without using X-ray radiation. It is particularly useful for examining the arteries in the brain, neck, kidneys, and legs. You will lie still inside a large tube-shaped MRI machine. Some MRA exams use an intravenous contrast dye called gadolinium to make vessels more visible; others do not require any contrast at all. The machine makes loud knocking sounds during the scan, and you will be given earplugs. The exam takes 30 to 90 minutes. You must remove all metal objects and inform staff of any implants. People with kidney disease should inform the doctor before gadolinium contrast is used.

An MRI uses powerful magnets and radio waves — not radiation — to create detailed images of soft tissues, organs, and the nervous system. You will lie still on a table that slides into a long, tube-shaped machine. The scan takes 20 to 90 minutes depending on the body part being examined. The machine makes loud knocking and thumping noises; you will be given earplugs or headphones. You must remove all metal objects and inform staff of any implants, pacemakers, or metal fragments in your body. Some scans use a contrast agent injected into a vein. MRI is especially useful for brain, spine, and joint conditions where soft tissue detail is important.

MRSA is a type of staph bacteria that has become resistant to many common antibiotics, making it harder to treat. It can cause skin infections that appear as red, swollen, painful bumps that may look like a pimple or boil, sometimes with pus. MRSA can also cause more serious infections of the bloodstream, lungs, and bones. It spreads through skin-to-skin contact or touching contaminated surfaces. Healthcare-associated MRSA occurs in hospitals and nursing facilities, while community-associated MRSA spreads in gyms and crowded settings. Treatment requires specific antibiotics that still work against MRSA. Good hand hygiene and keeping wounds covered help prevent spread.

ICD-10: A49

Multiple sclerosis (MS) is a chronic disease of the central nervous system in which the immune system attacks the protective myelin sheath covering nerve fibers, disrupting signals between the brain and body. Symptoms vary widely and may include numbness, weakness, vision problems, fatigue, balance issues, and cognitive changes. MS often presents in relapsing-remitting episodes. It affects more women than men and typically appears between ages 20 and 50. While there is no cure, disease-modifying therapies can reduce relapses and slow progression, and rehabilitation helps maintain daily function.

ICD-10: G35

Muscle pain, medically called myalgia, is soreness, aching, or tenderness in one or more muscles. It often develops after physical activity, overuse, or injury. Muscles may feel sore, tight, or bruised to the touch. Common causes include exercise-induced soreness, flu or viral infections, tension, dehydration, and conditions like fibromyalgia or lupus. Most muscle pain goes away with rest, gentle stretching, heat or ice, and over-the-counter pain relievers within a few days. See a provider if the pain is severe, involves significant muscle weakness, does not improve with rest, or is accompanied by a rash, fever, or dark-colored urine.

ICD-10: M79

A muscle spasm is a sudden, involuntary contraction of one or more muscles that can cause intense, localized pain. The muscle may feel hard, visibly twitch, or stay contracted for seconds to minutes. Spasms commonly affect the back, neck, legs, and feet. They can be triggered by dehydration, electrolyte imbalances, muscle overuse or fatigue, poor blood circulation, nerve irritation, or holding a position too long. Most muscle spasms resolve on their own. Stretching the affected muscle, applying heat, staying hydrated, and gentle massage can help. See a provider if spasms are frequent, severe, do not improve, or occur alongside weakness or significant pain.

Muscle weakness is a reduction in the strength of one or more muscles, making it difficult to perform normal movements such as climbing stairs, lifting objects, or rising from a chair. It can affect one area or the whole body. Causes include neurological conditions such as stroke, multiple sclerosis, or Guillain-Barré syndrome; muscle diseases; electrolyte imbalances; thyroid problems; vitamin D deficiency; and certain medications. Sudden weakness on one side of the body may signal a stroke and requires emergency care. Gradual or progressive weakness should be evaluated by a doctor, who may order blood tests, imaging, and nerve conduction studies.

ICD-10: M62

Muscular dystrophy refers to a group of inherited genetic diseases that cause progressive weakness and degeneration of skeletal muscles used for movement. The most common and severe form is Duchenne muscular dystrophy, affecting mostly males from early childhood. Symptoms typically begin with difficulty walking, frequent falls, and trouble rising from the floor, and progress to wheelchair use. Heart and breathing muscles can also be affected. There is no cure, but therapies including corticosteroids, gene therapy advances, physical therapy, and respiratory support help slow progression and improve quality of life.

ICD-10: G71

The myocardium is the muscle that makes up the wall of the heart. Unlike skeletal muscles you can voluntarily control, the myocardium contracts automatically and continuously — about 100,000 times a day — to pump blood throughout the body. It is supplied with oxygen through the coronary arteries. During a heart attack, part of the myocardium is deprived of blood and begins to die. Doctors measure an enzyme called troponin in the blood to detect myocardium damage — high troponin levels are a sign that heart muscle cells have been injured. Cardiomyopathy is a disease of the myocardium that weakens or stiffens the heart muscle over time.

Nail changes include any unusual alteration in the color, texture, shape, or thickness of the fingernails or toenails. Examples include yellowing, white spots, pitting, ridges, thickening, brittleness, curling inward or outward, or separation from the nail bed. These changes can result from fungal infections, psoriasis, iron deficiency anemia, thyroid disorders, liver or kidney disease, heart conditions, or nutritional deficiencies. Some nail changes are cosmetic; others point to systemic illness. A healthcare provider or dermatologist can examine nails and, if needed, order tests to determine whether the changes reflect an underlying medical problem requiring treatment.

The nasal septum is the thin wall of cartilage and bone that divides the inside of your nose into two separate passages — left and right nostrils. In many people, the septum is not perfectly centered; this is called a deviated septum. A severely deviated septum can partially or fully block one nostril, making breathing difficult, causing frequent nosebleeds, and worsening snoring or sleep apnea. Deviated septums can be present from birth or result from a nose injury. A surgical procedure called septoplasty can straighten the septum to improve airflow. The nasal septum may also be injured during trauma to the nose, or affected by infections, cocaine use, or certain inflammatory diseases.

A nasogastric (NG) tube is a thin, flexible tube passed through the nose, down the throat, and into the stomach. In hospitals, it is used for several purposes: to deliver liquid nutrition or medications to patients who cannot eat by mouth, to remove stomach contents (decompression) in cases of obstruction or overdose, or to sample stomach fluid for diagnostic testing. Placement involves the tube being inserted while you are awake, which may feel uncomfortable. An X-ray confirms correct placement. The tube is taped to your nose and connected to a bag or pump. Tell your nurse if you feel pain, nausea, or discomfort.

Nausea is the unpleasant sensation of feeling like you might vomit. It can be mild and passing or severe and prolonged. Very common causes include viral gastroenteritis (stomach flu), motion sickness, food poisoning, pregnancy, side effects from medications, and migraine headaches. Nausea can also signal more serious conditions such as appendicitis, gallbladder disease, kidney stones, heart attack, or a bowel obstruction. Seek medical care if nausea is severe, lasts more than two days without improvement, is accompanied by severe abdominal pain, chest pain, fever, or signs of dehydration such as decreased urination or dizziness.

ICD-10: R11

An NCT Number (National Clinical Trial number) is the unique identifier assigned by ClinicalTrials.gov—the U.S. federal registry of clinical studies—to every registered clinical trial. It begins with 'NCT' followed by eight digits. You can search ClinicalTrials.gov by NCT number to find a study's official description, eligibility criteria, locations, sponsor, and current status. If you are considering joining a clinical trial, always confirm the NCT number matches the study your provider mentioned. Under the ACA, insurance plans may be required to cover routine care costs for patients enrolled in approved clinical trials, and the NCT number helps document your enrollment when seeking that coverage.

A nebulizer treatment converts liquid medication into a fine mist that you inhale directly into your lungs through a mask or mouthpiece. It is used to deliver bronchodilators, steroids, or antibiotics for conditions such as asthma, COPD, cystic fibrosis, or respiratory infections. Each session typically takes ten to twenty minutes. Nebulizers are especially helpful for people who have difficulty using a standard inhaler, including young children or those with severe breathing difficulties. The medication acts quickly to open airways, reduce inflammation, or fight infection in the lungs.

Neck pain is discomfort in any of the structures in the neck, including muscles, nerves, bones, or discs between vertebrae. It can feel like stiffness, achiness, or sharp pain, and may limit your ability to turn your head. Common causes include muscle strain from poor posture or sleeping in an awkward position, whiplash, herniated discs, or arthritis. Most neck pain improves on its own within days to weeks with rest, heat or ice, and gentle stretching. Seek urgent care if neck pain follows a serious injury, is accompanied by fever, severe headache, or numbness and weakness in your arms or hands.

ICD-10: M54

Neonatal jaundice is a yellowing of a newborn's skin and eyes caused by a buildup of bilirubin, a byproduct of red blood cell breakdown. It is very common, affecting more than half of all newborns. Mild jaundice usually appears 2 to 3 days after birth and resolves within 2 weeks with frequent feeding. More severe jaundice, or jaundice appearing within 24 hours of birth, needs treatment — usually phototherapy (placing the baby under special blue-spectrum lights). Untreated very high bilirubin levels can cause brain damage. Your baby's bilirubin level will be checked before discharge and possibly again at a follow-up visit.

ICD-10: P59

A nerve block is a procedure in which anesthetic medication is injected near specific nerves to numb a region of the body, preventing pain signals from reaching the brain. Nerve blocks can be used for pain relief during surgery, as part of anesthesia, or for chronic pain management. Types include epidural blocks, spinal blocks, and peripheral nerve blocks such as those used before arm or leg surgery. The injection is guided by ultrasound, X-ray, or landmark technique. The procedure takes five to 30 minutes depending on the type. Effects can last from a few hours to several months depending on the medication used. Nerve blocks can reduce the need for opioid pain medications after surgery.

A nerve conduction study measures how fast and how strongly electrical signals travel through your nerves. Small electrode patches are placed on your skin over the nerve being tested. A mild electrical pulse is sent through one electrode, and the response is recorded at another. You will feel a brief tingling or shock-like sensation with each pulse, which can be mildly uncomfortable but is not harmful. The test usually lasts 20 to 60 minutes. It is used to diagnose conditions such as carpal tunnel syndrome, peripheral neuropathy, and nerve injuries. NCS is often done together with an EMG to get a complete picture of nerve and muscle health. Let your doctor know if you have a pacemaker.

Network adequacy refers to federal and state standards requiring that a health insurance plan's provider network includes a sufficient number and variety of providers — including primary care, specialists, hospitals, and mental health professionals — close enough to where enrollees live and work. Regulators set time-and-distance standards (e.g., a primary care doctor within 15 miles) and wait-time standards to define adequate access. If a plan's network is inadequate and you cannot access in-network care, you may have the right to request an out-of-network provider at in-network cost. Network adequacy protects patients from being unable to use the coverage they pay for.

A network exception, sometimes called a network gap exception or out-of-network exception, is a formal approval from your insurance company allowing you to receive care from an out-of-network provider at in-network cost-sharing rates. You may qualify if no in-network provider in your area offers the specialty or service you need, or if your current treating physician is not in your plan's network and continuity of care requires you to remain with that provider. You must request a network exception in writing and typically need supporting documentation from your doctor. Approvals are not guaranteed and may be granted for a limited time period.

Neuralgia is intense, stabbing, or burning pain along the course of a nerve, caused by nerve irritation or damage. Common types include trigeminal neuralgia (severe face pain), postherpetic neuralgia (pain following shingles), and occipital neuralgia (pain at the back of the head). The pain may come in brief, intense bursts triggered by touch, chewing, or movement, or it may be continuous. It can be extremely disabling. Causes include infections such as shingles, nerve compression, diabetes, multiple sclerosis, and injury. Treatment options include anticonvulsant medications, antidepressants, nerve blocks, or surgical procedures, depending on the type and severity.

ICD-10: M79

Neuropathic pain is caused by damage to or dysfunction of the nervous system itself, rather than by injury to body tissue. The nervous system sends incorrect pain signals even when there is no ongoing physical harm. It is often described as burning, shooting, stabbing, or electric shock-like. Patients may also experience numbness, tingling, or unusual sensitivity to touch. Common causes include diabetes (diabetic neuropathy), shingles, chemotherapy side effects, multiple sclerosis, spinal cord injuries, and nerve entrapment. Neuropathic pain can be hard to treat. Medications such as certain antidepressants, anticonvulsants, and topical creams are often used, in addition to nerve blocks and other interventional therapies.

Neutrophils are the most common type of white blood cell, making up about 50 to 70 percent of all white blood cells. They are the immune system's first responders to bacterial infection and inflammation. When bacteria or fungi invade the body, neutrophils rush to the site, engulf the invaders, and destroy them. Neutrophils live for only hours to days. A low neutrophil count (called neutropenia) dramatically increases the risk of serious infection and is often a side effect of chemotherapy or certain medications. Doctors monitor neutrophil levels closely in cancer patients receiving treatment. A high neutrophil count usually signals a bacterial infection, tissue injury, or significant physical stress.

Newborn screening is a public health program that tests every baby born in the US for a set of serious but treatable health conditions. Within 24 to 48 hours of birth, a small blood sample is taken from the baby's heel and sent to a state lab. Most states screen for more than 30 conditions including phenylketonuria (PKU), sickle cell disease, congenital hypothyroidism, and cystic fibrosis. Hearing screening and a heart defect check are also part of the standard newborn screen. Early detection allows treatment to begin before symptoms appear, preventing intellectual disability or death.

ICD-10: Z13

Night sweats are episodes of heavy sweating during sleep that soak clothes and bedding, even when the room is not too warm. They differ from normal warmth-related sweating and often signal an underlying medical cause. Common causes include menopause, low blood sugar, hyperthyroidism, infections such as tuberculosis and HIV, certain cancers including lymphoma, and medications such as antidepressants. Night sweats that are persistent, severe, or accompanied by fever, unexplained weight loss, swollen lymph nodes, or fatigue should be evaluated by a doctor promptly. They are usually not a 911 emergency but indicate that a medical workup is needed.

ICD-10: R61

The No Surprises Act is a federal law effective January 1, 2022, that protects patients from unexpected medical bills. It limits what out-of-network providers can charge patients in emergencies, or when an out-of-network provider is used at an in-network facility without the patient's informed consent. Under this law, patients pay no more than in-network cost-sharing amounts in these situations. Providers and insurers must resolve payment disputes through an independent dispute resolution process. The law also requires providers to give good-faith cost estimates before scheduled services. Violations can be reported to the federal government.

Nociceptive pain is the most common type of pain, caused by actual or potential damage to body tissue—skin, muscles, bones, or organs. Special nerve endings called nociceptors detect harmful stimuli (heat, pressure, chemicals) and send a pain signal to the brain. This type of pain is a protective mechanism; it tells you that something in your body is injured or at risk. It can feel sharp, aching, or throbbing. Examples include a cut on your finger, a broken bone, a bruised muscle, or arthritis in a joint. Nociceptive pain usually improves as the tissue heals and responds well to standard pain medications such as NSAIDs or acetaminophen.

A non-covered service is a medical service, treatment, or supply that your health insurance plan will not pay for. It may be excluded from your plan because it is not deemed medically necessary, it is considered cosmetic, it is experimental or investigational, or your plan specifically excludes it. Common examples include cosmetic surgery, routine eye exams under some plans, adult dental care, and certain weight-loss procedures. If you receive a non-covered service, you are generally responsible for the full cost. Your plan's Evidence of Coverage document lists exclusions. Always check whether a service is covered before receiving it to avoid large unexpected bills.

A Non-Quantitative Treatment Limitation (NQTL) is a non-numeric restriction a health plan places on mental health or substance use disorder benefits—such as prior authorization requirements, step therapy protocols, network design decisions, reimbursement rates, or medical necessity criteria. Under the Mental Health Parity and Addiction Equity Act (MHPAEA), NQTLs applied to mental health and substance use benefits must be no more restrictive than those applied to comparable medical or surgical benefits in the same benefit classification. If your insurer requires prior authorization for mental health therapy but not for comparable medical visits, that may violate parity. You can request your plan's comparative analysis and file a complaint with your state insurance department.

A Notice of Action (NOA) is a written document your Medicaid managed care plan or insurer must send when it takes an action affecting your benefits—such as denying a requested service, reducing your current coverage, or terminating your enrollment. The notice must explain the reason for the action, cite the specific rule or regulation behind it, and describe your right to appeal along with the deadline. Under Medicaid rules, you must receive advance notice before ongoing services are reduced or ended, giving you time to request that benefits continue while your appeal is pending. Read every NOA carefully and note the appeal deadline, because missing it can forfeit your right to challenge the decision.

A Notice of Observation Treatment—also called the Medicare Outpatient Observation Notice (MOON)—is a required written notice hospitals must give Medicare and Medicaid beneficiaries receiving hospital services under observation status rather than formal inpatient admission. This distinction has major financial consequences: inpatient status qualifies you for Medicare Part A hospital benefits and skilled nursing facility coverage after discharge, while observation status is billed under Part B outpatient rules, often resulting in higher drug copays and no SNF eligibility. You must receive the MOON within 36 hours of beginning observation status and sign it to acknowledge receipt—signing does not mean you agree with the classification.

NSAIDs are a class of medications that relieve pain, reduce fever, and decrease inflammation. Common NSAIDs include ibuprofen (Advil, Motrin) and naproxen (Aleve). Prescription-strength NSAIDs such as celecoxib are also available. They are commonly used for arthritis, menstrual cramps, back pain, and headaches. NSAIDs can irritate the stomach lining, so taking them with food or milk is recommended. Long-term use or high doses can increase the risk of stomach ulcers, kidney problems, and heart issues. Avoid NSAIDs if you have kidney disease, certain heart conditions, or are taking blood thinners without first talking to your doctor.

A nuclear medicine scan uses small amounts of radioactive material called radiotracers to evaluate organ function and detect disease. The tracer is usually given through an injection, swallowed, or inhaled. It travels to the organ being studied, where it emits gamma rays detected by a special camera called a gamma camera. This produces images that show how well an organ is working, not just what it looks like. Common examples include thyroid scans, HIDA scans for the gallbladder, and bone scans. The wait time between tracer injection and imaging varies from minutes to several hours. The radiation exposure is generally low and the tracer leaves your body within hours to days through urine or stool.

Numbness is a loss or reduction of sensation in a part of the body, often described as feeling nothing when you touch the skin. It can occur in the hands, feet, arms, legs, or face. Common causes include staying in one position too long, nerve compression such as carpal tunnel syndrome, vitamin deficiencies, diabetes, multiple sclerosis, or poor circulation. Sudden numbness on one side of the body — especially the face, arm, or leg — is a warning sign of stroke and requires calling 911 immediately. Persistent or widespread numbness without an obvious cause should be evaluated by a doctor to rule out serious nerve or vascular conditions.

ICD-10: R20

The nurse call button is a device located near your hospital bed—usually attached to the bed rail or a cord—that allows you to alert nursing staff when you need assistance. Pressing it activates a light outside your room and an alert at the nurses' station. Use it any time you need help: to use the bathroom, if you feel pain or discomfort, if your IV alarm is beeping, or if you are concerned about a sudden change in your condition. Do not try to get out of bed without calling first if you feel weak or dizzy, as falls are a serious hospital risk. Staff will respond as quickly as possible based on urgency.

An agreement among participating U.S. states that allows registered nurses and licensed practical nurses to hold a single multistate license. A nurse with a compact license can practice in any member state—in person or via telehealth—without obtaining an additional state license. Over 40 states participate as of 2024. This matters for patients using telehealth, because the nursing staff supporting your virtual visit may be licensed under a compact state. Nurses must follow the practice laws of the state where the patient is physically located, not where the nurse is based.

Nutritional counseling is a service provided by a registered dietitian (RD) or registered dietitian nutritionist (RDN) to assess your eating habits, health goals, and medical conditions, and then create a personalized nutrition plan. It is used to manage or prevent conditions such as diabetes, obesity, heart disease, kidney disease, eating disorders, and food allergies. Sessions involve reviewing your diet, discussing food choices, setting realistic goals, and providing ongoing support and education. Nutritional counseling may occur in clinics, hospitals, or via telehealth. Multiple sessions are often needed for meaningful dietary change and health improvement.

Obesity is a chronic medical condition defined by an excessive amount of body fat that increases the risk of other health problems. It is typically measured using body mass index (BMI), with obesity defined as a BMI of 30 or higher. Excess weight puts strain on the heart, joints, and organs. It raises the risk of type 2 diabetes, heart disease, high blood pressure, sleep apnea, and certain cancers. Causes include a combination of genetics, diet, physical activity levels, and environment. Treatment includes structured eating plans, increased physical activity, behavioral counseling, medications, and in some cases bariatric surgery.

ICD-10: E66

Observation status is a billing classification used when a hospital keeps you for monitoring or treatment but has not formally admitted you as an inpatient. Even if you stay overnight, you are considered an outpatient if placed under observation. This distinction matters greatly for Medicare patients, because Medicare Part B covers observation services at a higher cost-sharing than inpatient Part A coverage. Importantly, Medicare typically does not count observation days toward the three-day inpatient stay requirement for skilled nursing facility coverage. Ask your hospital whether you have been admitted or are under observation, as this affects your total costs significantly.

The occipital lobe is found at the very back of each brain hemisphere. It is the brain's main visual processing center. Signals from your eyes travel through the optic nerves to reach the occipital lobe, where your brain interprets shapes, colors, movement, and spatial depth to create the images you see. Both occipital lobes together process your entire visual field. Damage to the occipital lobe can cause vision loss even if your eyes are perfectly healthy. A stroke at the back of the brain may cause you to go blind in part of your visual field. Visual migraines with flashing lights or zigzag patterns are often caused by temporary changes in occipital lobe activity.

An occupational health evaluation is a medical assessment performed by an occupational medicine physician or nurse to evaluate a worker's health in relation to their job. It may be required before starting a new job, after a workplace injury or illness, or as part of ongoing fitness-for-duty monitoring. The evaluation typically includes a physical examination, review of medical history, functional testing, review of job demands, and sometimes laboratory or imaging tests. The goal is to determine whether a worker is able to safely perform their job duties, identify any work-related health risks, and recommend accommodations or treatments if needed.

Occupational therapy helps you regain or improve your ability to perform everyday tasks — such as dressing, cooking, writing, or using a computer — after illness, injury, or disability. A licensed occupational therapist assesses how your condition affects daily life and works with you on practical skills and adaptations. Sessions may include exercises to build fine motor skills, training with adaptive equipment, home safety assessments, and strategies for managing fatigue or pain. The goal is to maximize independence and quality of life in your home, workplace, and community.

OCD is a mental health condition characterized by recurring, unwanted thoughts (obsessions) that create anxiety and repetitive behaviors or mental acts (compulsions) performed to reduce that anxiety. Common obsessions include fears of contamination, harm, or making mistakes. Compulsions might include excessive handwashing, checking, counting, or repeating words silently. OCD is not about being overly neat or cautious — it is a condition that can significantly interfere with daily life. Effective treatment includes Exposure and Response Prevention therapy (ERP), a specialized form of cognitive behavioral therapy, and sometimes medication. Many people see substantial improvement with consistent, evidence-based care. Ask for a referral to an OCD specialist.

ICD-10: F42

Off-label drug use refers to prescribing an FDA-approved medication for a purpose, patient population, dosage, or route of administration not included in the FDA-approved labeling. This is legal and common in medical practice — estimates suggest 20–60% of prescriptions in certain specialties are off-label. Physicians may prescribe off-label based on clinical evidence, published studies, or expert consensus. However, insurers may deny coverage for off-label uses unless prior authorization is obtained with supporting clinical justification.

The olfactory nerve is the first cranial nerve and is responsible for your sense of smell. Specialized smell receptor cells high inside your nasal cavity detect odor molecules when you breathe in. These cells send signals through tiny nerve fibers that pass through small holes in a bone at the base of the skull, then connect to the olfactory bulbs — paired structures just above the nasal cavity inside the skull. From there, the signals travel to the brain's smell-processing areas, including areas linked to memory and emotion. This is why certain smells can trigger strong memories. Head injuries can shear the delicate olfactory nerve fibers, causing loss of smell (anosmia). COVID-19 infection was also found to commonly cause temporary or persistent anosmia.

Open Enrollment is the annual period when individuals can enroll in, change, or drop health insurance coverage without a qualifying life event. For Marketplace plans, federal open enrollment typically runs from November 1 to January 15. Employer-sponsored plans have their own open enrollment windows, usually in the fall. Outside of open enrollment, changes are only allowed during Special Enrollment Periods triggered by qualifying events such as job loss, marriage, or the birth of a child.

The operating room (OR) is a sterile room in a hospital where surgeries are performed by surgeons, anesthesiologists, nurses, and surgical technicians. Before going to the OR, you will sign a consent form and meet the anesthesiologist. You will be put under anesthesia (general or regional) so you do not feel pain. The OR is kept extremely clean to prevent infection, and only authorized personnel may enter. After surgery, you are moved to the recovery room (PACU) until you wake up. In emergencies, surgery may begin very quickly. It is normal to feel anxious; ask questions about the procedure and anesthesia beforehand.

Opioids are powerful prescription pain medications that work by binding to receptors in the brain and spinal cord to block pain signals. Common opioids include oxycodone, hydrocodone, morphine, and codeine. They are typically prescribed for severe acute pain, cancer pain, or pain that has not responded to other treatments. Opioids carry a significant risk of dependence, addiction, and overdose. Never take more than prescribed or share them with others. Avoid alcohol and sedatives while taking opioids. Do not stop suddenly without medical guidance. If you or someone else suspects an overdose, use naloxone (Narcan) and call 911 immediately.

Opioid use disorder is a medical condition involving problematic use of opioids — including prescription pain medications like oxycodone or hydrocodone, or illicit opioids like heroin and fentanyl. It is characterized by strong cravings, inability to control use, continued use despite harm, and withdrawal symptoms when stopping. Opioid use disorder is a chronic illness driven by changes in the brain, not a lack of willpower. In the US, it is highly treatable. Medications like buprenorphine (Suboxone), methadone, and naltrexone are FDA-approved and significantly reduce overdose risk, cravings, and withdrawal. These medications can be prescribed by certified providers in outpatient settings. Call SAMHSA at 1-800-662-4357 for help finding local treatment.

ICD-10: F11

The optic nerve is a bundle of over a million nerve fibers that carries visual information from your retina to your brain. Each eye has its own optic nerve. The nerve exits the back of the eyeball and travels to the brain, where the two optic nerves cross at a junction called the optic chiasm. After crossing, the signals travel to the occipital lobe for processing. Glaucoma is a common disease that damages the optic nerve, often due to elevated pressure inside the eye. Inflammation of the optic nerve, called optic neuritis, can cause sudden vision loss and is sometimes associated with multiple sclerosis. The health of the optic nerve is checked during routine eye exams.

The orbit is the bony socket in your skull that houses and protects your eyeball. Each eye sits in its own orbit, surrounded by a cone-shaped cavity formed by seven skull bones. The orbit cushions the eyeball with fat and connective tissue and contains the muscles that move the eye, as well as the blood vessels and nerves that supply the eye and surrounding structures. The optic nerve exits the back of the orbit through an opening in the bone called the optic canal. Fractures of the orbit (called orbital fractures or blowout fractures) can occur from direct impacts to the eye area, such as from a fist or ball. Infections, tumors, or inflammatory conditions can cause a bulging eye (proptosis) by increasing pressure within the orbit.

Organ transplantation is surgery to replace a failing or diseased organ with a healthy one from a donor. Common transplants include kidney, liver, heart, lung, and pancreas. The donor may be a living person (for kidney or part of liver) or a deceased donor. Recipients must be matched carefully to reduce the risk of rejection. After transplant, patients must take immunosuppressant medications for life to prevent the immune system from attacking the new organ. The surgery and recovery are complex, often involving weeks in the hospital. Close follow-up is required for life. There can be a long wait for a donated organ, and the process is coordinated through national transplant organizations.

Original Medicare is the traditional federal health insurance program for people 65 and older and certain individuals with disabilities. Part A covers inpatient hospital stays, skilled nursing facility care, hospice, and some home health services. Part B covers doctor visits, outpatient services, preventive care, and durable medical equipment. You pay premiums, deductibles, and coinsurance for each part separately. Original Medicare does not cap annual out-of-pocket costs, so many enrollees add a Medigap supplemental policy or a Part D prescription drug plan for additional financial protection.

In Medicare telehealth billing, the originating site is the physical location where the patient receives a telehealth service. Before the COVID-19 pandemic, Medicare required originating sites to be approved facilities—such as rural health clinics, federally qualified health centers, or hospitals—not a patient's home. Pandemic-era flexibilities temporarily allowed patients' homes to qualify. Whether your home counts as an originating site affects whether Medicare will reimburse your virtual visit. Your provider or billing department can tell you if your location qualifies under current CMS rules.

Orthopnea is the inability to breathe comfortably when lying flat, forcing a person to sit up or use extra pillows to sleep. It is a classic symptom of heart failure, where fluid that pools in the lower body when upright shifts to the lungs when lying down, making breathing difficult. It can also occur with severe obesity, asthma, or COPD. The number of pillows needed to breathe comfortably can help gauge severity. See your doctor promptly if you develop this symptom. If breathlessness when lying flat is sudden or very severe, call 911 — it may signal acute pulmonary edema, a life-threatening emergency.

ICD-10: R06

Osteoarthritis is the most common form of arthritis, caused by the gradual breakdown of cartilage—the cushioning tissue inside joints. As cartilage wears away, bones rub together, causing pain, stiffness, and swelling, especially in the knees, hips, hands, and spine. Symptoms often worsen with activity and improve with rest. Daily life may be affected by difficulty walking, climbing stairs, or gripping objects. Treatment focuses on pain management through medications, physical therapy, weight control, and in severe cases, joint replacement surgery.

ICD-10: M19

Osteoporosis is a condition in which bones become weak and brittle due to loss of bone density, increasing the risk of fractures from minor falls or even everyday activities. It is most common in older women after menopause but can affect anyone. Often called a "silent" disease because there are no symptoms until a fracture occurs, commonly in the hip, spine, or wrist. Treatment includes calcium and vitamin D supplements, weight-bearing exercise, and medications such as bisphosphonates to strengthen bones and reduce fracture risk.

ICD-10: M81

OTC, or over-the-counter, medications are drugs you can purchase at a pharmacy or retail store without a doctor's prescription. Common OTC medications include pain relievers like ibuprofen and acetaminophen, antacids, allergy medicines, and cold remedies. Although they do not require a prescription, OTC medications are regulated by the FDA for safety and effectiveness. Some OTC drugs can still cause serious side effects, interact with prescription medications, or be unsafe during pregnancy. Always read the label carefully and inform your doctor and pharmacist about all OTC products you take regularly, as they can affect your overall treatment plan.

Otitis media is an infection or inflammation of the middle ear — the space behind the eardrum. It is the most common infection for which children in the US receive antibiotics. Symptoms include ear pain (a young child may pull at their ear), fever, irritability, difficulty sleeping, and temporarily reduced hearing. It often follows a cold. Most cases resolve on their own, and pediatric guidelines now recommend a "watch and wait" approach for mild cases in children over 2. Antibiotics are prescribed for severe cases, children under 2, or when symptoms do not improve. Repeated ear infections may require ear tubes.

ICD-10: H66

An out-of-network provider does not have a contract with your insurance plan. Using one typically results in higher costs: higher deductibles, higher coinsurance, and sometimes full billing at list prices. Some plan types (HMO, EPO) do not cover out-of-network care at all except in emergencies. Balance billing — being billed the difference between the provider's charge and the insurer's payment — is a risk when going out of network, though the No Surprises Act restricts this in emergency settings.

The out-of-pocket maximum is the most you will have to pay for covered in-network services in a plan year. Once you reach this limit — through deductibles, copays, and coinsurance combined — your insurance covers 100% of covered services for the rest of the year. ACA-compliant plans set federal limits on out-of-pocket maximums annually. Premiums, out-of-network costs, and services not covered by the plan do not count toward this limit.

Outpatient care includes any medical treatment, procedure, or visit where the patient does not require an overnight hospital stay. This includes doctor office visits, same-day surgery, emergency room visits, urgent care, imaging, and laboratory tests. Outpatient care is generally subject to different cost-sharing than inpatient: under Medicare, outpatient services fall under Part B rather than Part A, which has different deductibles and coinsurance. Many procedures that previously required hospitalization are now done on an outpatient basis.

Outpatient mental health services are mental health treatment and support provided in a community or clinic setting without an overnight hospital stay. This is the most common level of mental health care in the US and includes individual therapy sessions, group therapy, psychiatric medication management appointments, and intensive outpatient programs (IOP). Outpatient care is appropriate for people whose symptoms are manageable with scheduled appointments and do not require round-the-clock supervision. Insurance plans subject to the Mental Health Parity and Addiction Equity Act must cover outpatient behavioral health visits on the same terms as outpatient medical visits. To find in-network providers, contact your insurer's member services or use their online provider directory.

Ovarian cancer is a malignant tumor of the ovaries, the organs that produce eggs and hormones in women. It is often called a 'silent killer' because it typically causes few symptoms in early stages and is frequently diagnosed at an advanced stage. Symptoms may include bloating, pelvic pain, difficulty eating, and frequent urination. BRCA gene mutations significantly increase risk. There is currently no standard screening test for ovarian cancer in average-risk women. Treatment includes surgery and chemotherapy. Early detection greatly improves outcomes.

ICD-10: C56

The ovaries are two small, almond-sized organs in a woman's pelvis, one on each side of the uterus. They have two main functions: producing eggs (ova) that can be fertilized and potentially lead to pregnancy, and producing the hormones estrogen and progesterone, which regulate the menstrual cycle and support pregnancy. Each month, usually one egg matures and is released during ovulation. Common ovarian problems include cysts (fluid-filled sacs), polycystic ovary syndrome (PCOS), ovarian torsion (twisting), and ovarian cancer. Symptoms like pelvic pain, bloating, or irregular periods should be reported to your doctor. Ultrasound is commonly used to view the ovaries.

Oxygen saturation (SpO2) measures the percentage of hemoglobin in your blood that is carrying oxygen. It is typically measured with a small clip called a pulse oximeter placed on a finger. Normal oxygen saturation for healthy adults is 95 to 100 percent. A reading below 90 percent is considered dangerously low and is a medical emergency requiring supplemental oxygen or urgent breathing support. Conditions such as pneumonia, asthma, COPD, and COVID-19 can lower oxygen saturation. Hospital staff will increase your oxygen supply or escalate care quickly if your saturation drops below safe levels.

Oxygen therapy delivers supplemental oxygen to patients whose blood oxygen levels are too low to support normal body function. It may be provided through nasal cannulas, masks, or high-flow devices in a hospital, clinic, or at home. Conditions that may require oxygen therapy include COPD, pneumonia, heart failure, and sleep apnea. Home oxygen is prescribed when your blood oxygen saturation consistently falls below safe levels. The therapy helps relieve shortness of breath, improve energy, protect organ function, and in chronic conditions, extend life. Equipment may include portable tanks or an oxygen concentrator.

Pacemaker implantation is a surgical procedure in which a small electronic device is placed under the skin near the collarbone to regulate an abnormal heart rhythm. Thin wires called leads are threaded through veins into the heart chambers to deliver small electrical signals that keep the heart beating at a steady rate. The procedure is performed under local anesthesia with sedation and typically takes one to two hours. Most patients go home the next day. You will need to avoid heavy lifting for several weeks and stay clear of strong magnetic fields. Follow-up appointments are needed to check the device and battery life.

Pain management is a medical specialty focused on evaluating, diagnosing, and treating chronic or complex pain conditions. It may involve a combination of approaches including medications (such as anti-inflammatories, nerve blocks, or controlled substances), physical therapy, injections, spinal cord stimulation, cognitive strategies, and complementary therapies. A pain management specialist works with you to identify the source of your pain and develop a personalized plan to reduce its intensity and impact on daily life. The goal is to improve function and quality of life, not necessarily to eliminate pain entirely.

The pain scale is a tool used by hospital staff to understand how much pain you are experiencing. The most common version asks you to rate your pain from 0 (no pain) to 10 (worst pain imaginable). Some facilities use visual scales with facial expressions for children or people who cannot speak. Nurses document your pain score and reassess it after treatments. Accurately reporting your pain helps ensure you receive appropriate medication or interventions. Do not underreport your pain thinking it is unimportant. Your comfort is part of your medical care and affects outcomes, including your ability to breathe and recover.

Painful urination, medically called dysuria, is a burning, stinging, or aching sensation felt when urinating. It is one of the most common symptoms of a urinary tract infection (UTI), which is more common in women than men. Other causes include sexually transmitted infections, kidney stones, urethritis, interstitial cystitis, vaginal infections, and prostatitis in men. A burning sensation localized to the opening of the urethra at the end of urination is a classic UTI sign. Painful urination that is new, severe, accompanied by fever, back pain, blood in the urine, or discharge should be evaluated by a doctor promptly.

ICD-10: R30

The palate is the roof of your mouth. It is divided into two parts. The hard palate is the rigid front portion — it is formed by bone covered with a thin layer of tissue and separates your mouth from your nasal cavity. The soft palate is the flexible, fleshy part at the back, which includes the uvula (the small dangling tissue you can see at the back of your throat). The soft palate rises to close off the nasal passage when you swallow, preventing food and liquid from going up your nose. Cleft palate is a birth defect where the palate does not close completely during fetal development. The palate also plays an important role in speech and snoring.

Pale skin refers to an abnormal lightening of the skin, often noticed on the face, lips, gums, or inner eyelids. It can signal reduced blood flow or a drop in red blood cell levels. Common causes include anemia, blood loss, shock, fright, or fainting. Chronic causes include iron, vitamin B12, or folate deficiency, thyroid disease, kidney disease, and certain blood cancers. Pallor combined with fatigue, dizziness, or shortness of breath should be evaluated promptly. Your doctor will typically order a complete blood count to check for anemia and other blood abnormalities.

Palliative care is specialized medical care focused on providing relief from the symptoms, pain, and stress of a serious illness. It can be provided alongside curative treatment at any stage of illness — it is not only for end-of-life situations. A palliative care team of doctors, nurses, and social workers works with you and your other doctors to provide an extra layer of support. Goals include managing pain, fatigue, nausea, depression, and anxiety; improving communication between patients and medical teams; and supporting both patients and their families in making informed decisions about care.

The pancreas is a long, flat gland about six inches long that sits deep in the abdomen behind the stomach. It has two main jobs. As an exocrine gland, it produces digestive enzymes — powerful chemicals that flow into the small intestine through the pancreatic duct to break down proteins, fats, and carbohydrates. As an endocrine gland, it produces hormones directly into the bloodstream — most importantly insulin and glucagon, which regulate blood sugar levels. Diabetes occurs when the pancreas either cannot make enough insulin or the body cannot use it properly. Pancreatitis — inflammation of the pancreas — can be caused by gallstones or heavy alcohol use and causes severe abdominal pain.

Pancreatitis is inflammation of the pancreas, a gland behind the stomach that produces digestive enzymes and hormones like insulin. In pancreatitis, the digestive enzymes activate while still in the pancreas and begin attacking the organ itself. Acute pancreatitis comes on suddenly and causes severe upper abdominal pain that often radiates to the back, nausea, vomiting, and fever. Common causes include gallstones and heavy alcohol use. Chronic pancreatitis develops gradually over time and can damage the pancreas permanently, impairing digestion and blood sugar regulation. Treatment depends on severity and may include hospitalization, IV fluids, pain management, dietary changes, and treating the underlying cause.

ICD-10: K85

A panic attack is a sudden episode of intense fear that triggers severe physical reactions even when there is no real danger. Symptoms can include a racing or pounding heart, chest pain, shortness of breath, dizziness, trembling, sweating, and a feeling that something terrible is about to happen. Panic attacks typically peak within ten minutes and usually subside within half an hour. Having repeated panic attacks may indicate panic disorder. While panic attacks are not medically dangerous, they can be very frightening and disruptive. Treatment includes therapy — especially cognitive behavioral therapy — breathing techniques, and sometimes medication. Let your doctor know if you are having these episodes regularly.

ICD-10: F41

A Pap smear (also called a Pap test or cervical cytology) screens for cervical cancer and abnormal cervical cells that could become cancerous if untreated. During a pelvic exam, a clinician gently inserts a speculum into the vagina, then uses a small brush or spatula to collect cells from the surface of the cervix. The sample is sent to a lab, where technicians examine the cells under a microscope. The test takes only a few minutes. Women typically begin Pap screening at age 21 and repeat every three years, or every five years when combined with HPV testing. Catching cell changes early allows treatment before cancer develops.

Paracentesis is a procedure in which a needle or thin catheter is inserted through the abdominal wall to remove fluid that has accumulated in the abdominal cavity (the peritoneal space). This fluid buildup, called ascites, is commonly caused by liver disease, cirrhosis, cancer, or heart failure. The procedure is done under local anesthesia and typically takes 20 to 45 minutes. Ultrasound guidance helps ensure accurate needle placement. Large amounts of fluid, sometimes several liters, can be removed to relieve discomfort, swelling, and difficulty breathing. A sample of the fluid may be sent for laboratory testing to look for infection or cancer cells. Patients generally feel relief quickly and go home the same day.

Paralysis is the complete loss of muscle function in one or more parts of the body, making normal movement impossible. It may affect an arm, leg, one entire side (hemiplegia), or all four limbs (quadriplegia). Causes include stroke, spinal cord injury, multiple sclerosis, Guillain-Barré syndrome, and brain tumors. Sudden paralysis — especially on one side of the body — is a medical emergency and the classic stroke warning sign. Call 911 immediately. Even if paralysis resolves on its own within minutes, it could indicate a transient ischemic attack (TIA or mini-stroke), which requires urgent evaluation to prevent a full stroke. Do not wait.

ICD-10: G83

A paramedic is an advanced pre-hospital healthcare provider with higher training than an EMT. Paramedics can perform advanced life support procedures, including placing breathing tubes (intubation), administering a wider range of medications, interpreting heart rhythm strips, and performing cardiac monitoring. They work in ambulances and emergency helicopters and communicate with physicians by radio to receive guidance during emergencies. If a paramedic is treating you, it usually means your condition is more serious. Paramedics document their care, which becomes part of your medical record at the hospital. Their rapid interventions often save lives before hospital arrival.

The parietal lobe sits at the top and back of each brain hemisphere, behind the frontal lobe. Its main job is to process sensory information from your body — things like touch, pain, temperature, and where your limbs are in space (called proprioception). The parietal lobe helps you understand spatial relationships, so you can navigate a room or judge distances. It also plays a role in reading, writing, and arithmetic. Damage to the parietal lobe can cause difficulty with spatial awareness, trouble writing, or problems identifying objects by touch alone. Right-side parietal lobe damage can cause a condition where patients ignore one side of their body or their environment.

Parkinson's disease is a progressive neurological disorder caused by the loss of dopamine-producing neurons in the brain, which impairs movement control. The most recognizable symptoms are tremors at rest, muscle rigidity, slowness of movement (bradykinesia), and balance problems. Over time it can affect speech, swallowing, facial expression, and cognition. It is most common in adults over 60. While there is no cure, medications such as levodopa-carbidopa help manage symptoms, and deep brain stimulation is an option for some patients when medications become less effective.

ICD-10: G20

A participating provider is a doctor, hospital, or other healthcare provider that has signed a contract with an insurance company to accept the plan's negotiated rates as payment in full for covered services. Also called an in-network provider, a participating provider agrees not to bill you more than your required cost-sharing (deductible, copay, or coinsurance) based on the allowed amount. Seeing a participating provider generally results in lower out-of-pocket costs. Before scheduling care, always verify your provider's participation status with your specific plan — provider networks change, and a provider may participate in some of an insurer's plans but not others.

The patella, commonly called the kneecap, is the small, triangular bone that sits at the front of your knee. It acts as a shield to protect the knee joint and helps the muscles around your knee work more efficiently. The patella slides within a groove at the bottom of the femur when you bend and straighten your leg. It is surrounded and held in place by tendons and ligaments. Injuries such as a dislocated or fractured kneecap cause significant pain and swelling. Conditions like patellofemoral syndrome cause pain behind or around the kneecap, often felt when climbing stairs or squatting.

A patient assistance program (PAP) is a manufacturer-run program that provides free or heavily discounted brand-name prescription medications to qualifying patients who have low income, lack insurance, or have inadequate drug coverage. Eligibility requirements vary by drug and manufacturer but typically include proof of income, a current prescription, and a completed application. Many major pharmaceutical companies operate PAPs, and nonprofit enrollment assistance organizations can help you apply. If your medication is unaffordable, ask your doctor or hospital social worker about available PAPs, or search the drug manufacturer's website for application instructions.

A payment plan is a formal agreement between you and a hospital, clinic, or provider to repay a medical bill in smaller, scheduled installments over time rather than a single lump sum. Many facilities offer interest-free payment plans, particularly for low-income patients, and some will reduce or forgive balances through charity care. Federal rules require hospitals to offer payment plans before sending accounts to debt collection. Always ask the billing department about payment plan options before the bill is sent to a collector—once a bill goes to collections, your options narrow significantly.

Pediatric asthma is a chronic lung disease that causes the airways to swell and narrow, leading to wheezing, coughing (especially at night), chest tightness, and shortness of breath. It is the most common chronic disease of childhood in the US, affecting about 6 million children. Triggers include allergens (pet dander, dust mites, mold), respiratory infections, cold air, and exercise. Treatment involves two main types of medications: quick-relief (rescue) inhalers for sudden symptoms, and long-term controller medications (such as inhaled corticosteroids) to prevent attacks. An asthma action plan helps parents and schools respond correctly when symptoms worsen.

ICD-10: J45

A pediatric growth chart is a standardized graph that tracks your child's height, weight, and head circumference over time compared to other children of the same age and sex in the US. It uses percentiles — for example, a child at the 50th percentile is average compared to peers; at the 25th percentile they are smaller than 75% of peers. Growth charts used by US pediatricians are developed by the CDC (for children 2 and older) and the World Health Organization (for babies under 2). What matters most is consistent growth along a curve, not the percentile number itself.

Pediatric strep throat is a bacterial throat infection caused by Group A Streptococcus (GAS). It is most common in school-age children, especially ages 5 to 15. Symptoms include a sudden, severe sore throat, pain when swallowing, fever, and swollen neck glands. Unlike a virus, strep does not cause a cough or runny nose. A rapid strep test at the doctor's office confirms the diagnosis. Treatment requires a full course of antibiotics (usually amoxicillin) to prevent rare but serious complications such as rheumatic fever, which can damage the heart. Children can return to school 24 hours after starting antibiotics and once fever-free.

ICD-10: J02

A pediatrician is a medical doctor (MD or DO) who specializes in the care of infants, children, and adolescents from birth through age 18. Pediatricians provide well-child checkups, diagnose and treat illnesses, administer vaccines, track growth and developmental milestones, and refer to specialists when needed. In the US, it is recommended to choose a pediatrician before your baby is born so they can see your newborn within a few days of discharge. Pediatricians complete at least 3 years of specialized residency training after medical school. General practitioners (family medicine doctors) can also provide pediatric care, especially in rural areas.

A peer support specialist is a certified professional with personal lived experience of a mental health condition, substance use disorder, or serious illness who uses that experience to help others navigate recovery. They provide emotional support, share coping strategies, and connect people to community resources. Many states have formal certification requirements. Peer support specialists are employed by behavioral health clinics, hospitals, and community organizations. Under mental health parity laws, peer support services provided by certified specialists may be covered by insurance the same way as other behavioral health visits.

Pelvic pain is discomfort in the lower abdomen or pelvis, which is the area between the belly button and groin. It can feel like cramping, pressure, heaviness, or sharp stabbing pain. In women, it is often related to the menstrual cycle, ovarian cysts, endometriosis, or uterine fibroids. In both men and women, it can stem from bladder or bowel problems, pelvic floor muscle issues, or infection. Chronic pelvic pain lasting more than six months deserves a thorough evaluation. Seek urgent care if the pain is sudden and severe, accompanied by fever, heavy vaginal bleeding, or inability to urinate.

ICD-10: R10

The pelvis is the bowl-shaped ring of bones at the base of your spine, connecting your spine to your legs. It is made up of two large hip bones on each side, the sacrum in the back, and the coccyx (tailbone) below. The pelvis supports and protects organs in your lower abdomen, including the bladder, parts of the intestines, and in women, the uterus and ovaries. It also transfers weight from the upper body to your legs. Pelvic fractures can be serious and often result from high-energy trauma like car accidents. Pelvic pain in women may relate to reproductive organs.

A peptic ulcer is an open sore that develops on the inner lining of the stomach, upper small intestine, or esophagus. Most peptic ulcers are caused by infection with Helicobacter pylori bacteria or long-term use of nonsteroidal anti-inflammatory drugs such as ibuprofen or aspirin. Symptoms include burning stomach pain, bloating, heartburn, nausea, and in severe cases vomiting blood or passing dark stools. Treatment typically involves antibiotics to eradicate H. pylori and acid-suppressing medications such as proton pump inhibitors. Avoiding NSAIDs, alcohol, and smoking helps healing. Untreated ulcers can lead to serious complications such as bleeding or perforation.

ICD-10: K27

Pericarditis is inflammation of the pericardium, the thin, two-layered, fluid-filled sac surrounding the heart. The most common cause is viral infection, but it can also result from autoimmune diseases, bacterial infections, heart attack, or as a reaction to certain medications. The hallmark symptom is sharp chest pain that often worsens when lying down and improves when sitting up and leaning forward. Other symptoms include fever and shortness of breath. Most cases of acute pericarditis are self-limiting and respond well to anti-inflammatory medications such as NSAIDs and colchicine. Recurrent pericarditis may require additional treatment.

ICD-10: I30

The pericardium is a tough, double-layered sac made of fibrous tissue that surrounds and protects the heart. Think of it as a protective bag wrapped around the heart. A small amount of fluid between the two layers lubricates the heart so it can beat smoothly without friction. Pericarditis is inflammation of this sac, which causes sharp chest pain that often feels worse when lying down and better when sitting forward. Fluid can accumulate between the two layers — called a pericardial effusion — and if enough builds up it can press on the heart and prevent it from filling properly, a dangerous condition called cardiac tamponade that requires emergency drainage.

Peripheral artery disease (PAD) occurs when narrowed arteries reduce blood flow to the limbs, most commonly the legs. The narrowing is caused by plaque buildup in the artery walls. Symptoms include leg pain or cramping when walking that goes away with rest (called claudication), numbness, weakness, and slow-healing sores on the feet or legs. PAD is a sign of widespread arterial disease and raises the risk of heart attack and stroke. Treatment includes quitting smoking, exercise programs, medications to improve blood flow, and in severe cases procedures to open or bypass blocked arteries.

ICD-10: I70

Peripheral neuropathy is damage to the peripheral nerves—those outside the brain and spinal cord—causing weakness, numbness, tingling, and pain, typically in the hands and feet. It can result from diabetes (the most common cause), infections, autoimmune diseases, vitamin deficiencies, alcohol use, or certain medications. Symptoms may include burning or electric pain, balance problems, and in severe cases, muscle weakness or paralysis. Treatment focuses on addressing the underlying cause and managing symptoms through medications for nerve pain, physical therapy to maintain function, and lifestyle modifications to prevent progression.

ICD-10: G62

Peritoneal dialysis is a kidney replacement therapy done at home using the lining of your abdomen — the peritoneum — as a natural filter. A catheter is surgically placed in your belly, and a cleansing fluid called dialysate is introduced and later drained through the catheter. This process removes waste and extra fluid from your blood. You may do several exchanges per day (continuous ambulatory peritoneal dialysis) or use a machine overnight (automated peritoneal dialysis). It offers flexibility compared to in-center hemodialysis and allows greater independence for many patients with kidney failure.

The peritoneum is a thin, smooth membrane that lines the inside of the abdominal cavity and covers most of the abdominal organs, including the stomach, intestines, liver, and spleen. It acts like a slippery lining that lets organs move smoothly against each other. A small amount of fluid between its two layers reduces friction. Peritonitis — inflammation of the peritoneum, usually caused by a bacterial infection from a ruptured appendix, perforated ulcer, or abdominal injury — is a medical emergency requiring immediate surgery and antibiotics. Abdominal surgeries that leave scar tissue can cause adhesions — bands of tissue that form between organs and the peritoneum, sometimes causing bowel obstructions later.

Pernicious anemia is a type of anemia caused by the body's inability to absorb vitamin B12 properly. Vitamin B12 is essential for making red blood cells and maintaining a healthy nervous system. Absorption requires a protein called intrinsic factor made in the stomach. In pernicious anemia, an autoimmune process destroys the stomach cells that make intrinsic factor, leading to B12 deficiency. Symptoms include fatigue, weakness, pale or yellowish skin, shortness of breath, numbness or tingling in the hands and feet, and difficulty with balance and memory. Treatment involves regular vitamin B12 injections or, in some cases, high-dose oral B12 supplements.

ICD-10: D51

Under HIPAA, a personal representative is someone legally authorized to make healthcare decisions on behalf of a patient—including parents of minors, court-appointed guardians, and holders of a valid healthcare power of attorney. A personal representative has the same right to access, request, and amend a patient's medical records as the patient themselves. Providers must treat a properly identified personal representative as if they were the patient for all HIPAA purposes. Providers may decline this status if recognizing the representative could endanger the patient.

A PET scan shows how your organs and tissues are functioning by detecting a small amount of radioactive tracer injected into your bloodstream. Cancer cells and active disease areas absorb more tracer and appear as bright spots on the images. You will need to fast for four to six hours beforehand and avoid strenuous exercise the day before. After the tracer injection, you will wait about an hour while it travels through your body. The scan itself lasts 30 to 45 minutes while you lie still in the machine. PET scans are often combined with CT imaging to provide both functional and structural information. The radiation exposure is low and the tracer leaves your body within hours.

A pharmacist is a licensed healthcare professional with doctoral-level training who specializes in medications and their safe, effective use. At your pharmacy, the pharmacist reviews your prescriptions, verifies that the dose is appropriate for your condition and weight, screens for dangerous drug interactions, counsels you on how to take your medication correctly, and answers questions about side effects. Pharmacists also provide immunizations, medication therapy management services, and guidance on over-the-counter products. They are among the most accessible members of your healthcare team. Do not hesitate to ask your pharmacist questions about any prescription or nonprescription medication you take.

The pharynx is the muscular tube at the back of your throat that connects your nose and mouth to your esophagus (food pipe) and larynx (voice box). It is about five inches long and is divided into three sections: the nasopharynx (behind the nose), oropharynx (behind the mouth), and hypopharynx (just above the larynx). When you swallow, the pharynx contracts to push food and liquids downward while closing off the airway to prevent choking. The pharynx also plays a role in speech and in hearing, as the Eustachian tube opens into the nasopharynx. Infections like pharyngitis (strep throat) and conditions like sleep apnea involve the pharynx.

A phobia is an intense, persistent, and excessive fear of a specific object, situation, or activity that poses little or no actual danger. Common phobias include fear of heights, flying, spiders, needles, blood, or enclosed spaces. When exposed to the feared object or situation, a person with a phobia may experience immediate anxiety, panic, or a strong urge to flee. Phobias can significantly limit daily activities and quality of life. The most effective treatment is a type of therapy called Exposure Therapy, in which a therapist gradually and safely helps you face the feared stimulus. Most people see significant improvement with targeted, brief treatment. Ask your doctor for a referral to a cognitive behavioral therapist.

ICD-10: F40

Phototherapy uses controlled exposure to specific wavelengths of light to treat certain skin conditions or mood disorders. For skin conditions such as psoriasis, eczema, or vitiligo, ultraviolet (UV) light — typically UVB — is delivered in a medical booth or handheld device under clinical supervision. For seasonal affective disorder (SAD), a bright light therapy lamp is used to expose the patient to a high-intensity light source in the morning. Sessions are brief, typically lasting seconds to minutes for UV phototherapy, or twenty to thirty minutes for light therapy for mood. Response usually develops over several weeks of regular treatment.

Physical therapy uses exercise, manual techniques, and specialized equipment to help you recover from injury, surgery, or illness that affects your ability to move. A licensed physical therapist evaluates your strength, flexibility, balance, and pain levels, then designs a personalized treatment plan. Sessions typically last forty-five to sixty minutes and may include stretching, strengthening exercises, heat or ice application, ultrasound, and hands-on manipulation. The goal is to reduce pain, restore function, prevent future injury, and help you return to daily activities or sports safely.

A pill is a general, everyday term for any small solid medication you swallow, including tablets and capsules. In clinical settings, pharmacists prefer more specific terms, but patients and providers commonly use pill in conversation. Some pills are scored, meaning they have a line across the middle allowing them to be split in half when a lower dose is needed. However, not all pills can be safely cut or crushed, especially extended-release or enteric-coated formulations. Always check with your pharmacist before splitting, crushing, or chewing a pill, since altering some pill types can release too much medication at once, causing dangerous effects.

The pituitary gland is a pea-sized gland located at the base of the brain, just behind the bridge of your nose. Despite its small size, it is often called the master gland because it controls most other hormone-producing glands in your body. It releases hormones that regulate growth, blood pressure, thyroid function, reproduction, metabolism, and the body's response to stress. The pituitary works closely with the hypothalamus, which sits just above it. Tumors on the pituitary gland, called pituitary adenomas, are usually benign but can cause hormone imbalances or press on nearby structures like the optic nerves, affecting vision.

A placebo is an inactive substance, device, or procedure used in clinical trials as a comparison to the experimental treatment. Participants may receive either the real treatment or a placebo without knowing which they received — this is called blinding. The placebo effect refers to real physiological improvements some patients experience even when receiving an inactive treatment, due to expectation and belief. Placebos are critical to rigorous clinical research design. Outside of trials, providing placebos without disclosure to patients raises ethical concerns.

The placenta is an organ that develops in the uterus during pregnancy. It attaches to the wall of the uterus and connects to the developing baby through the umbilical cord. The placenta's job is to pass oxygen and nutrients from the mother's blood to the baby, and to carry waste products from the baby back to the mother. It also produces hormones that support the pregnancy. After the baby is born, the placenta is delivered — this is called the afterbirth. Problems such as placenta previa (low placement blocking the cervix) or placental abruption (early separation from the uterine wall) are serious complications that need immediate medical attention.

Placenta previa occurs when the placenta — the organ that feeds your baby — lies low in the uterus and partially or completely covers the cervical opening. This can cause painless vaginal bleeding, especially in the third trimester. If the placenta remains over the cervix close to your due date, a vaginal birth is not safe, and a cesarean delivery will be planned. Placenta previa is usually identified on a routine ultrasound. Your provider will likely advise pelvic rest (no sex, no vaginal exams) and may restrict activity. Bleeding that is heavy or doesn't stop is a medical emergency.

ICD-10: O44

Placental abruption happens when the placenta separates from the uterus wall before delivery. This cuts off oxygen and nutrients to the baby and causes bleeding for the mother. Symptoms include sudden abdominal pain, back pain, and vaginal bleeding — though sometimes bleeding stays hidden inside the uterus. It is a medical emergency. Severity ranges from mild to complete separation. Risk factors include high blood pressure, prior abruption, trauma to the abdomen, smoking, and cocaine use. Depending on how far along you are and how severe the abruption is, your care team may recommend immediate delivery.

ICD-10: O45

A plan year is the 12-month period during which your health insurance benefits are active. Your deductible, out-of-pocket maximum, and other cost accumulators reset to zero at the start of each new plan year. Employer-sponsored plans often run on a plan year different from the calendar year—for example, July 1 to June 30. Understanding when your plan year starts and ends helps you time elective procedures and expensive services to make the most of what your insurance has already applied to your deductible during that year.

Plantar fasciitis is one of the most common causes of heel pain, caused by inflammation of the plantar fascia—a thick band of tissue that connects the heel bone to the toes along the bottom of the foot. The hallmark symptom is sharp, stabbing heel pain with the first steps in the morning or after long periods of rest. It is common in runners, people who stand for long hours, and those with flat feet or high arches. Treatment includes stretching exercises, supportive footwear, orthotics, ice, anti-inflammatory medications, and cortisone injections when symptoms persist.

ICD-10: M72

Plasma is the liquid portion of your blood, making up about 55 percent of total blood volume. It is a pale yellow fluid composed mostly of water (about 92 percent), along with dissolved proteins, nutrients, hormones, waste products, and clotting factors. Plasma transports red blood cells, white blood cells, and platelets throughout the body, and carries nutrients from digestion to organs. It also helps regulate blood pressure and body temperature. Plasma proteins such as albumin and fibrinogen play important roles in clotting, immune defense, and maintaining fluid balance. Plasma can be donated separately from whole blood and is used in medical treatments for burn patients, trauma victims, and people with clotting disorders.

Platelets are tiny, disc-shaped cell fragments in the blood that play a critical role in clotting. When you have a cut or injury, platelets rush to the damaged area, clump together, and form a plug to stop bleeding. They also release chemicals that attract more platelets and activate clotting proteins. Platelets are produced in the bone marrow and live for about seven to ten days. A low platelet count (thrombocytopenia) can cause easy bruising, prolonged bleeding, or tiny red spots on the skin called petechiae. A high count (thrombocytosis) can increase the risk of blood clots. Platelet counts are measured with a standard complete blood count (CBC) test.

The pleura is a thin two-layered membrane — a smooth, slippery lining — that wraps around each lung and also lines the inside of the chest wall. The two layers slide against each other as you breathe, and a tiny amount of fluid between them acts like a lubricant so breathing is painless and effortless. When the pleura becomes inflamed — a condition called pleuritis or pleurisy — you may feel a sharp stabbing pain in the chest with every breath. Fluid can also build up between the two layers, a condition called a pleural effusion, which can compress the lung and cause shortness of breath. Doctors can drain this fluid with a needle procedure called a thoracentesis.

Pleural effusion is the buildup of excess fluid between the two layers of tissue that surround the lungs, called the pleura. It can be caused by heart failure, pneumonia, cancer, kidney disease, or autoimmune conditions. Symptoms include shortness of breath, chest pain that worsens with breathing, and a dry cough. Small effusions may resolve without treatment. Larger ones may require thoracentesis, a procedure where a needle drains the fluid to relieve pressure and allow testing of the fluid. Treatment depends on the underlying cause and may include diuretics, antibiotics, or drainage procedures. A persistent effusion requires specialist evaluation.

ICD-10: J90

Pneumonia is an infection of one or both lungs where the air sacs fill with fluid or pus. It can be caused by bacteria, viruses, or fungi. Common symptoms include cough with phlegm, fever, chills, and difficulty breathing. Bacterial pneumonia is usually treated with antibiotics, while viral pneumonia may require antiviral medications. Mild cases can be managed at home with rest and fluids, but severe cases require hospitalization, especially in older adults, young children, or people with weakened immune systems. Vaccines are available to prevent some common causes of pneumonia.

ICD-10: J18

Pneumothorax occurs when air leaks into the space between the lung and chest wall, causing the lung to collapse partially or completely. It can happen spontaneously, especially in tall thin young adults, or result from a chest injury, medical procedure, or underlying lung disease such as COPD. Symptoms include sudden sharp chest pain and shortness of breath. A small pneumothorax may heal on its own with rest, while a large one requires a chest tube to remove the trapped air and allow the lung to re-expand. A tension pneumothorax is a medical emergency where trapped air compresses the heart and requires immediate intervention.

ICD-10: J93

Polycystic ovary syndrome (PCOS) is a hormonal disorder common in women of reproductive age, characterized by irregular or infrequent menstrual periods, excess androgen (male hormone) levels, and multiple small cysts on the ovaries. Symptoms may include irregular periods, excess facial or body hair (hirsutism), acne, weight gain, and difficulty getting pregnant. PCOS is also associated with insulin resistance and an increased risk of type 2 diabetes and metabolic syndrome. Treatment focuses on managing symptoms and may include birth control pills, metformin, lifestyle changes, and fertility medications for women trying to conceive.

ICD-10: E28

Polycythemia is a condition in which the body produces too many red blood cells, making the blood thicker than normal. Polycythemia vera is the primary form, caused by a genetic mutation in the bone marrow. Secondary polycythemia can result from chronic low oxygen levels (such as in sleep apnea or living at high altitude) or other underlying conditions. Thickened blood increases the risk of blood clots, stroke, and heart attack. Symptoms may include headaches, dizziness, itching after bathing, and red skin. Treatment includes phlebotomy (removing blood), aspirin, and medications to reduce blood cell production.

ICD-10: D45

Polymyalgia rheumatica (PMR) is an inflammatory condition causing aching and stiffness in the shoulders, neck, upper arms, hips, and thighs, typically in adults over 50. The pain and stiffness are usually worst in the morning and can significantly limit daily activities such as dressing, raising arms, or rising from a chair. It is associated with giant cell arteritis, a serious complication involving inflammation of blood vessels. PMR responds dramatically to low-dose corticosteroids such as prednisone, which are the primary treatment, though long-term use requires monitoring for side effects.

ICD-10: M35

Poor appetite, also called anorexia, means having little or no desire to eat. It commonly accompanies illnesses such as infections, digestive problems, cancer, chronic kidney disease, liver disorders, depression, anxiety, and thyroid conditions. Medications including chemotherapy, antibiotics, and certain pain relievers can also suppress appetite. In older adults, poor appetite can lead to weight loss and nutritional deficiencies. Short-term appetite loss during an illness is usually temporary. However, a persistent lack of appetite lasting more than a few days, especially with weight loss or other symptoms, should be discussed with a healthcare provider to identify the underlying cause.

A port-a-cath, also called an implanted port or venous access port, is a small device surgically placed under the skin in the chest. It connects to a catheter that leads into a large vein near the heart. The port allows repeated access to a vein for giving chemotherapy, blood transfusions, IV medications, or drawing blood without repeatedly inserting new needles into peripheral veins. A special needle is inserted through the skin into the port for each use. The implantation procedure takes about 30 to 60 minutes under local anesthesia with sedation. The port can remain in place for months to years and requires regular flushing to prevent clotting. Infection and clotting are the most common complications.

The portal vein is a large blood vessel that carries nutrient-rich blood from the digestive organs — including the stomach, intestines, spleen, and pancreas — to the liver. After you eat, nutrients and other substances absorbed by the gut travel through the portal vein to the liver for processing, detoxification, and storage. The liver depends on this blood supply, which accounts for about seventy-five percent of its total blood flow. Portal hypertension — elevated blood pressure inside the portal vein — is a serious complication of liver cirrhosis. It can cause the development of large, tortuous veins called varices in the esophagus or stomach that can rupture and bleed severely.

Postpartum refers to the period after giving birth, typically defined as the first six weeks, though full recovery can take months. During this time your body heals from pregnancy and delivery: your uterus shrinks, hormone levels shift dramatically, and you may experience vaginal discharge called lochia. Common concerns include perineal soreness, breast engorgement, fatigue, and emotional changes including baby blues or postpartum depression. Your provider will schedule a postpartum visit, usually at 6 weeks (or earlier for C-section). The American College of Obstetricians and Gynecologists (ACOG) recommends ongoing support throughout the full postpartum period.

ICD-10: Z39

Postpartum coverage refers to health insurance benefits for the mother after childbirth. Federal law now requires state Medicaid programs to provide at least 12 continuous months of postpartum coverage to eligible mothers—a major expansion from the previous 60-day limit. This coverage is critical because many pregnancy-related complications, including postpartum depression, hemorrhage, and infection, emerge weeks or months after delivery. On private insurance, the mother's existing plan typically continues. If you recently gave birth and are on Medicaid, contact your state office to confirm your postpartum coverage end date.

Postpartum depression (PPD) is a mood disorder that can affect people after childbirth, going beyond the typical "baby blues" that resolve within two weeks. Symptoms include persistent sadness, feeling disconnected from your baby, crying spells, irritability, anxiety, sleep problems, and thoughts of harming yourself or your baby. PPD affects about 1 in 7 mothers and is not a sign of weakness or bad parenting. It is treatable with therapy, medication (including antidepressants safe during breastfeeding), and support groups. Your provider will screen for PPD at postpartum visits. Tell your provider right away if you are having any thoughts of harm.

ICD-10: F53

A PPO (Preferred Provider Organization) is an insurance plan offering more flexibility than an HMO. Members can see any doctor without a referral, including out-of-network providers, though in-network care costs less. PPOs typically have higher premiums than HMOs but allow self-referrals to specialists. Out-of-network coverage usually involves higher deductibles and coinsurance. PPOs suit people who value provider choice, travel frequently, or have complex conditions requiring multiple specialists.

A pre-existing condition is any health condition you had before your health insurance coverage began—such as diabetes, asthma, cancer, or heart disease. Under the Affordable Care Act, insurance companies in the individual and group markets cannot deny you coverage, charge higher premiums, or impose waiting periods because of a pre-existing condition. Before the ACA, insurers routinely refused coverage or charged substantially more. Short-term health plans and some grandfathered plans may not carry these protections, so check your specific plan's terms if you have a pre-existing condition.

Prediabetes means blood sugar levels are higher than normal but not yet high enough to be diagnosed as type 2 diabetes. It is a serious health condition because without lifestyle changes, prediabetes often progresses to type 2 diabetes within five years. It is also linked to increased risk of heart disease and stroke. Most people with prediabetes have no symptoms. It is detected through blood tests such as a fasting glucose test or an A1C test. The good news is that prediabetes is reversible with lifestyle changes. Losing 5 to 7 percent of body weight through healthy eating and regular physical activity can significantly reduce the risk of developing type 2 diabetes.

ICD-10: R73

Preeclampsia is a pregnancy complication marked by high blood pressure (at or above 140/90 mmHg) and signs of organ stress such as protein in the urine, severe headaches, vision changes, or swelling. It usually develops after 20 weeks of pregnancy. Without treatment it can progress to eclampsia, a life-threatening condition with seizures. Risk factors include first pregnancy, multiples, obesity, and prior history of high blood pressure. Delivery is the only cure. Your provider may monitor you closely, prescribe medication, or recommend early delivery depending on how severe the condition is.

ICD-10: O14

A preexisting condition is a health problem, illness, or injury you had before the start date of your current health insurance coverage — such as diabetes, cancer, asthma, or heart disease. Under the Affordable Care Act (ACA), health plans sold in the individual market and group market cannot deny coverage, charge higher premiums, or impose waiting periods based on preexisting conditions. This protection applies to all ACA-compliant plans, including Marketplace plans. However, some short-term health plans and grandfathered plans are exempt from this rule. Always verify whether a plan is ACA-compliant if you have a preexisting condition.

A premium is the monthly amount you pay to maintain your health insurance coverage, regardless of whether you use medical services that month. Premiums are paid to the insurance company and do not count toward your deductible or out-of-pocket maximum. Employer-sponsored plans often split premiums between employer and employee. Marketplace plans may qualify for Advanced Premium Tax Credits (APTC) that reduce monthly costs for eligible lower-income enrollees.

Prenatal care is the medical care you receive from a doctor, midwife, or nurse-midwife during pregnancy. It includes regular checkups to monitor your health and your baby's growth, blood tests, ultrasounds, and screenings for conditions like gestational diabetes and preeclampsia. Starting prenatal care early — ideally in the first trimester — improves outcomes for both mother and baby. Your provider will also answer questions about nutrition, exercise, warning signs, and birth planning. In the US, most insurance plans cover prenatal visits at no cost to you.

ICD-10: Z34

A prenatal ultrasound uses high-frequency sound waves to create images of your baby and uterus during pregnancy. A gel is applied to your abdomen, and a transducer is moved over the skin to capture images. Some early-pregnancy scans use a transvaginal probe inserted gently into the vagina for better images. The test is painless and safe for both mother and baby, as no radiation is used. Ultrasounds are used to confirm pregnancy, check the baby's growth and position, measure the amniotic fluid, detect structural abnormalities, and determine the due date. You may be asked to have a full bladder for some exams. Most pregnancies involve at least two scheduled ultrasounds.

Prescription-only medications, also labeled Rx, require a written or electronic order from a licensed healthcare provider such as a doctor, nurse practitioner, or physician assistant before a pharmacy can legally dispense them. These drugs are regulated this way because they may be dangerous without professional oversight, carry a risk of dependence, or require a diagnosis to be used safely. You cannot legally purchase prescription-only drugs at a store counter or online without a valid prescription. Once your prescription expires or all authorized refills are used, you must contact your provider to obtain a renewal before the pharmacy can fill it again.

Presumptive eligibility allows authorized entities—such as hospitals, community health centers, or schools—to grant temporary Medicaid coverage to individuals who appear likely to qualify while the formal state application is being processed. During this period you can receive covered services right away rather than waiting weeks for official approval. The period is short, typically ending when the state completes its eligibility determination or at the end of the following month. This provision is especially important for pregnant women, children, and people in acute medical situations who cannot afford to delay care.

Preterm labor is regular uterine contractions that begin before 37 weeks of pregnancy, causing the cervix to open. Babies born before 37 weeks are premature and may face breathing problems, feeding difficulties, and longer hospital stays. Symptoms include regular contractions (more than 5 in an hour), pelvic pressure, low backache, or fluid leaking from the vagina. Risk factors include prior preterm birth, multiple pregnancy, infections, and cervical conditions. Your provider may give medications to slow contractions, steroid injections to speed the baby's lung development, or antibiotics to treat infection.

ICD-10: O60

Preventive care refers to services designed to prevent illness or detect health conditions early before symptoms develop. Under the ACA, most insurance plans must cover a set of preventive services at no cost to the patient — with no deductible, copay, or coinsurance — when provided by an in-network provider. These services include annual wellness visits, vaccinations, cancer screenings (mammograms, colonoscopies), blood pressure and cholesterol checks, and certain medications for high-risk patients. The required services are based on recommendations from USPSTF, ACIP, and HRSA.

A primary care provider (PCP) is the main clinician responsible for your routine and preventive healthcare. PCPs include family physicians, general internists, pediatricians, nurse practitioners, and physician assistants. They perform annual wellness exams, manage chronic conditions such as diabetes and hypertension, order screening tests, prescribe medications, and refer you to specialists when needed. In HMO plans, your PCP often serves as a gatekeeper whose referral is required before seeing a specialist. Choosing a PCP who speaks your language or understands your cultural background can improve communication and outcomes.

A Primary Care Provider (PCP) is a physician, nurse practitioner, or physician assistant who serves as a patient's main healthcare contact for routine and preventive care. PCPs handle annual wellness visits, manage chronic conditions, prescribe medications, and coordinate referrals to specialists. Under HMO plans, designating a PCP is required and the PCP serves as the gatekeeper to specialized care. PCPs may be family medicine doctors, general internists, or pediatricians.

When you have more than one health insurance plan, the primary payer is the insurance company that processes and pays your medical claim first. The secondary insurer then covers some or all of the remaining balance. Coordination of benefits rules determine which plan pays first. For example, if you are covered by your own employer plan and your spouse's plan, specific rules govern priority. Medicare has special primary-payer rules depending on employer size, disability status, and whether you have end-stage renal disease.

A principal investigator (PI) is the lead scientist or physician responsible for designing and overseeing a clinical trial or research study. The PI ensures participant safety, protocol compliance, data integrity, and timely regulatory reporting. Before any study begins, the PI submits the research plan to an Institutional Review Board for ethical review and approval. As a trial participant, you can ask who the PI is and how to reach them. The PI is your primary point of contact if you experience an adverse event you believe is related to the study.

Prior auth is the shortened term for prior authorization, the insurer approval required before receiving certain medical services or medications. The terms are interchangeable. Without prior auth, the insurer may deny the claim or require the patient to pay full cost. Obtaining prior auth is the provider's responsibility in most cases, though patients can check with their insurer to confirm it has been obtained before a scheduled procedure. Prior auth decisions must meet federally mandated timeframes.

Prior authorization (PA) is approval from your insurance company required before you receive certain medical services, medications, or procedures. Without it, the insurer may deny the claim or pay a reduced amount. Common services requiring PA include surgery, MRI/CT scans, brand-name drugs, specialist visits under some plans, and durable medical equipment. The requesting provider submits clinical justification; approval decisions are typically required within set timeframes under state law.

A prior authorization denial occurs when your insurance company refuses to approve coverage for a requested service, treatment, or medication before it is provided. Common reasons include the insurer determining the service is not medically necessary, the treatment does not meet clinical criteria, or step therapy requirements were not followed. A denial letter must explain the reason and inform you of your right to appeal. You typically have the right to an internal appeal and then an external independent review. Urgent denials must be resolved within 72 hours; non-urgent cases within 30 days. Your provider can often supply additional information to overturn the denial.

PRN is a Latin abbreviation for pro re nata, meaning as needed. A PRN medication is one you take only when you experience a specific symptom, such as pain, nausea, anxiety, or shortness of breath, rather than on a fixed daily schedule. Your prescription will specify the maximum dose and how frequently you may take it within a given period. PRN medications suit symptoms that come and go, giving you flexibility to treat yourself when needed without taking medication constantly. Ask your doctor or pharmacist how to judge when it is appropriate to use your PRN medication and when you should seek emergency care instead.

Probate is the court-supervised legal process for settling a deceased person's estate. It includes validating the will, inventorying assets, paying outstanding debts, and distributing what remains to heirs. Medicaid programs are required by federal law to seek repayment from the estates of deceased beneficiaries who received long-term care after age 55—a process called Medicaid estate recovery. If a family member died while receiving Medicaid, the state may file a claim against their estate during probate. An estate planning attorney can help structure assets to minimize potential recovery before it occurs.

A procedure code identifies a medical service, treatment, or supply on an insurance claim. In the United States, procedure codes come from two main systems: CPT (Current Procedural Terminology, maintained by the AMA) for physician and outpatient services, and HCPCS Level II for ambulance services, durable medical equipment, drugs, and other items. Medicare and Medicaid require HCPCS codes. Procedure codes are paired with diagnosis codes on a claim so the insurer can verify that the service was medically necessary.

A productive cough is one that brings up mucus or phlegm from the lungs or airways. The color and consistency of the mucus can give important clues to your doctor: clear or white mucus often signals allergies or a viral infection, yellow or green mucus may indicate a bacterial infection, and pink, red, or rust-colored mucus can signal more serious conditions like pneumonia or heart failure. A productive cough that lasts more than three weeks, produces blood, or is accompanied by fever, chest pain, or significant fatigue should be evaluated promptly.

ICD-10: R05

Prospective review is a type of utilization review performed before a planned medical service or treatment takes place. This is the same process as prior authorization — the insurer evaluates whether a requested service is medically necessary and meets plan criteria before it is approved for coverage. Prospective review is commonly required for elective surgeries, specialty procedures, certain prescription drugs, inpatient admissions, and rehabilitation services. The goal is to prevent unnecessary or inappropriate care and control costs before expenses are incurred. Approval from a prospective review does not guarantee full payment; the insurer may still review the final claim to ensure the service provided matched what was approved.

The prostate is a small walnut-sized gland found only in men, located just below the bladder and in front of the rectum. It surrounds the urethra, the tube that carries urine and semen out of the body. The prostate produces some of the fluid that makes up semen. As men age, the prostate often grows larger — a condition called benign prostatic hyperplasia (BPH) — which can press on the urethra and make urination difficult. Prostate cancer is one of the most common cancers in men. A PSA blood test and digital rectal exam (DRE) are often used to screen for prostate problems.

Prostate cancer is a malignant tumor of the prostate gland, a walnut-sized gland in men that produces seminal fluid. It is the most common cancer in American men after skin cancer. Many prostate cancers grow slowly and may not cause symptoms for years. PSA blood tests and rectal exams help detect it early. Treatment options include active surveillance, surgery, radiation, hormone therapy, and chemotherapy. Early-stage prostate cancer is often very treatable. Talk to your doctor about when to start screening, especially if you have a family history.

ICD-10: C61

Protected health information (PHI) is any individually identifiable information about your health that is created, used, or stored by a covered healthcare entity or their business associate. PHI includes your name, address, date of birth, Social Security number, diagnoses, lab results, treatment records, and billing information. Under HIPAA, covered entities must safeguard PHI and cannot share it without your written authorization except in limited circumstances such as treatment, payment, or required public health reporting. You have the right to view your PHI, request corrections, and receive a record of who has accessed it.

The prothrombin time (PT) test measures how long it takes your blood to clot. The international normalized ratio (INR) converts that time into a standardized number so results can be compared across different laboratories. A blood sample is drawn from a vein in your arm. For most healthy adults, the INR is around 1.0. People taking blood-thinning medication (warfarin/Coumadin) are monitored regularly and typically kept in a therapeutic range of 2.0–3.0, depending on their condition. Doctors use PT/INR before surgery, to diagnose clotting disorders, to assess liver function (since the liver makes clotting proteins), and to monitor anticoagulant therapy.

In clinical research, a protocol is the detailed written plan governing how a study is designed and conducted. It specifies the study's scientific question, participant eligibility criteria, dosing schedules, required tests, safety monitoring procedures, and data collection methods. The protocol must be approved by an Institutional Review Board before the study begins. As a participant, you are entitled to a plain-language summary of the protocol. Any changes made after enrollment must go through a formal amendment process and typically require participants to re-consent before continuing.

Proton pump inhibitors (PPIs) reduce the amount of acid the stomach produces. They are used to treat gastroesophageal reflux disease (GERD), peptic ulcers, and H. pylori infection, and to protect the stomach during NSAID use. Common PPIs include omeprazole (Prilosec), pantoprazole (Protonix), and esomeprazole (Nexium). Take PPIs 30 to 60 minutes before your first meal for best results. PPIs are generally safe for short-term use, but long-term use may be associated with reduced magnesium and calcium absorption. If you have been on a PPI for more than a few months, ask your doctor whether you still need it.

A provider network is the set of doctors, hospitals, pharmacies, and other healthcare facilities that have contracted with an insurance plan to provide services at negotiated rates. Using in-network providers results in lower cost-sharing for the patient. Networks vary in size and geography — some plans have broad national networks while others, particularly HMO and EPO plans, have narrower local networks. Patients should verify network status directly with both the insurer and the provider, as directories can be outdated.

The PSA test measures the level of prostate-specific antigen, a protein produced by the prostate gland, in your blood. Elevated PSA can signal prostate cancer, but it can also be raised by a benign enlarged prostate (BPH), prostatitis (prostate inflammation), or vigorous physical activity. Blood is drawn from a vein in your arm. Some doctors recommend avoiding ejaculation and intense bike riding for 48 hours before the test as these can temporarily raise PSA. The test is used for early detection of prostate cancer in men, typically starting at age 50 (or earlier for those at higher risk), and to monitor treatment response for those already diagnosed.

Psoriasis is a chronic autoimmune skin disease that causes skin cells to multiply up to ten times faster than normal, resulting in red, scaly, thick patches on the skin. It most commonly affects the elbows, knees, scalp, and lower back. Psoriasis is not contagious. Flare-ups can be triggered by stress, infections, certain medications, and skin injury. Beyond skin symptoms, psoriasis is associated with psoriatic arthritis and increased risk of heart disease. Treatment options range from topical creams and light therapy to systemic medications and biologics.

ICD-10: L40

A psychiatric evaluation is a comprehensive assessment conducted by a psychiatrist or other mental health provider to understand your mental health history, current symptoms, and overall wellbeing. It typically includes a detailed interview covering your mood, thoughts, behavior, medical history, medications, family history, and any prior mental health treatment. Based on the evaluation, the provider may diagnose a mental health condition and recommend a treatment plan — which may include therapy, medication, or both. A psychiatric evaluation is often the first formal step in receiving mental health care, especially when medication might be part of treatment. Most insurance plans cover psychiatric evaluations from in-network providers. Ask your primary care doctor for a referral if needed.

A psychiatrist is a medical doctor (MD or DO) who specializes in diagnosing and treating mental health conditions. Because psychiatrists are physicians, they can prescribe psychiatric medications such as antidepressants, mood stabilizers, antipsychotics, and anti-anxiety medications. They conduct psychiatric evaluations and manage complex mental health conditions that require medical oversight. Many psychiatrists focus primarily on medication management and collaborate with therapists or psychologists who provide the ongoing talk therapy. Wait times for psychiatrists in the US can be long due to provider shortages — if you are waiting for a psychiatrist appointment, your primary care provider can often begin medication management for common conditions like depression and anxiety in the meantime.

A psychologist is a mental health professional who holds a doctoral degree (PhD, PsyD, or EdD) in psychology. Psychologists are trained in assessment, psychotherapy, and research. They conduct psychological testing and assessments to diagnose mental health conditions and learning disabilities, and they provide evidence-based therapy. In most US states, psychologists cannot prescribe medication — that remains the role of psychiatrists and primary care physicians, though a small number of states (such as Louisiana and New Mexico) allow specially trained psychologists to prescribe. Psychologists often work alongside psychiatrists in treatment teams. To see a psychologist, check that they are licensed in your state and in-network with your insurance plan.

Psychotherapy — also called talk therapy or counseling — is a range of treatments that help people understand and change thoughts, feelings, and behaviors that are causing them distress. It is delivered by licensed mental health professionals including psychologists, licensed clinical social workers, licensed counselors, and psychiatrists. Common evidence-based approaches include cognitive behavioral therapy (CBT), dialectical behavior therapy (DBT), psychodynamic therapy, and interpersonal therapy. Psychotherapy may be used alone or in combination with medication. Sessions are typically 45 to 60 minutes and may occur weekly or more frequently depending on need. Under the Mental Health Parity law, insurance plans that cover medical visits must cover psychotherapy visits on comparable terms. Check your plan's behavioral health benefits for details.

PTSD is a mental health condition that can develop after experiencing or witnessing a traumatic event such as violence, an accident, military combat, a natural disaster, or sexual assault. Symptoms include flashbacks, nightmares, severe anxiety, intrusive memories, feeling emotionally numb, avoiding reminders of the trauma, and hypervigilance. Not everyone who experiences trauma develops PTSD, and having PTSD is not a sign of weakness. It is a recognized medical diagnosis. Effective treatments include trauma-focused therapy such as Prolonged Exposure or EMDR, and certain medications. Veterans can access specialized PTSD care through the VA. Ask your provider for a trauma-informed referral.

ICD-10: F43

A pulmonary embolism (PE) is a blockage in one or more arteries in the lungs, usually caused by a blood clot that travels from the legs or elsewhere in the body. A large PE can be immediately life-threatening by blocking blood flow through the lungs. Symptoms include sudden shortness of breath, sharp chest pain that worsens with breathing, rapid heart rate, coughing up blood, and feeling faint. PE is a medical emergency requiring immediate care. Treatment includes blood-thinning medications, clot-dissolving drugs, or in severe cases surgical removal of the clot. Long-term anticoagulation therapy is usually required to prevent recurrence.

ICD-10: I26

Pulmonary fibrosis is a serious lung disease in which the lung tissue becomes scarred and thickened, making it harder for lungs to work properly. When no cause is identified it is called idiopathic pulmonary fibrosis. Causes can include long-term exposure to dust, toxins, certain medications, or autoimmune diseases. Symptoms include a dry persistent cough, progressive shortness of breath, fatigue, and unexplained weight loss. The scarring is irreversible. Medications such as nintedanib and pirfenidone may slow progression. Pulmonary rehabilitation, oxygen therapy, and eventually lung transplant may be options. Early diagnosis and specialist care are essential to managing this condition.

ICD-10: J84

Pulse oximetry is a quick, painless test that measures how much oxygen your blood is carrying. A small clip-like device called a pulse oximeter is placed on your fingertip, earlobe, or toe. It uses light beams to detect the color of your blood, which changes depending on how much oxygen it contains. Normal oxygen saturation is 95 to 100 percent. Results are displayed within seconds. The test is often done in a doctor's office, emergency room, or at home with a personal device. Cold fingers, nail polish, or poor circulation may affect accuracy. Pulse oximetry is used to monitor patients with breathing problems, heart conditions, or during or after surgery to ensure adequate oxygen levels.

Pulse rate, also called heart rate, is the number of times the heart beats per minute. In a hospital, it is measured by a clip placed on a finger (pulse oximeter) or by ECG leads on the chest. A normal resting pulse for adults is 60 to 100 beats per minute. A rate below 60 (bradycardia) or above 100 (tachycardia) may require evaluation. Very fast or irregular pulses can indicate a cardiac emergency. Nurses will alert you if your pulse rate sets off a monitor alarm, which usually means the reading needs to be checked rather than always indicating an emergency.

A qualified medical expense is a healthcare cost defined by the IRS under Section 213(d) that can be paid tax-free from a Health Savings Account (HSA), Flexible Spending Account (FSA), or Health Reimbursement Arrangement (HRA). Qualifying expenses include doctor visits, prescriptions, dental care, vision care, and many over-the-counter items. Cosmetic procedures and gym memberships are generally not qualified. Using HSA funds for non-qualified expenses triggers income tax plus a 20% penalty for holders under age 65. IRS Publication 502 provides the complete list of qualifying expenses.

A qualifying health plan (QHP) is a health insurance plan that meets minimum standards established by the Affordable Care Act and is certified to be sold on the Health Insurance Marketplace. QHPs must cover the ten essential health benefits, limit annual out-of-pocket costs, comply with preexisting condition protections, and meet other ACA standards. Purchasing a QHP on the Marketplace allows eligible individuals to receive premium tax credits and cost-sharing reductions. Not all ACA-compliant plans sold off the Marketplace are QHPs. Employer-sponsored plans that meet minimum value and affordability requirements are separately considered minimum essential coverage.

A qualifying life event is a change in circumstances that makes a person eligible for a Special Enrollment Period outside of open enrollment. Qualifying events include loss of health coverage (job loss, aging off a parent's plan at 26, loss of Medicaid eligibility), change in household (marriage, divorce, birth, adoption, death), change in residence to a new plan area, and certain other situations such as gaining citizenship or leaving incarceration. Each qualifying event has a specific enrollment window, typically 60 days.

A qualifying life event (QLE) is a change in your personal circumstances that makes you eligible to enroll in or change a health insurance plan outside of the annual Open Enrollment Period, triggering a Special Enrollment Period. Common qualifying life events include getting married or divorced, having or adopting a baby, losing job-based coverage, moving to a new coverage area, and becoming a U.S. citizen or lawfully present immigrant. You typically have 60 days from the event to select a new plan. Documentation is usually required to verify the event with the marketplace.

A quantitative treatment limitation (QTL) is a numeric cap on health insurance benefits—such as a limit of 20 covered therapy sessions per year or a cap on inpatient mental health days. Under the Mental Health Parity and Addiction Equity Act, QTLs applied to mental health and substance use disorder benefits must be no more restrictive than those applied to comparable medical or surgical benefits. If your plan limits therapy visits, ask whether the same cap applies to equivalent physical health benefits—if not, the plan may be violating federal parity law.

Radiating pain is pain that starts in one location and spreads or travels to other parts of the body along a nerve pathway. For example, sciatica causes pain that radiates from the lower back through the buttock and down the leg. Arm pain radiating from the shoulder can signal a pinched nerve. Chest pain radiating to the jaw, arm, or back may indicate a heart attack. Radiating pain is often caused by nerve compression, a herniated disc, or problems with organs such as the heart or kidneys. Because it can indicate serious conditions, radiating pain—especially in the chest or accompanied by other symptoms—should be evaluated by a provider promptly.

Radiation therapy uses high-energy beams — such as X-rays or protons — to destroy cancer cells or shrink tumors. A machine directs the beams precisely at the affected area while you lie still on a table. Most sessions last only a few minutes and are painless, though you may have several sessions per week over multiple weeks. Side effects depend on the body area treated and can include skin irritation, fatigue, or localized discomfort. Radiation may be used alone, before surgery to shrink a tumor, or after surgery to eliminate remaining cancer cells.

The radius is one of the two bones in your forearm, located on the thumb side. It runs from the elbow to the wrist and is the larger of the two forearm bones at the wrist end. The radius plays a key role in wrist movement and rotation of the forearm. It connects to the humerus at the elbow and to the wrist bones below. The most common type of forearm fracture is a distal radius fracture — a break near the wrist, often caused by falling on an outstretched hand. These fractures are very common and are sometimes called Colles fractures. Treatment may involve a cast or surgery.

A randomized controlled trial (RCT) is the gold-standard method for testing whether a new treatment works. Participants are randomly assigned—by chance, like a coin flip—to either the treatment group or the control group receiving standard care or a placebo. Random assignment eliminates selection bias and makes groups comparable. An RCT may also be 'blinded,' meaning participants, researchers, or both do not know who received which treatment. The FDA requires evidence from RCTs to approve most new drugs. As a participant, knowing your trial's design helps you understand what is already established about the treatment.

Rapid breathing, medically called tachypnea, means breathing faster than normal. In adults, a resting breathing rate above 20 breaths per minute is generally considered rapid. It can be a natural response to exercise, fear, or excitement, but persistent rapid breathing at rest is a warning sign. Causes include anxiety or panic attacks, fever, infection, asthma, pulmonary embolism, heart failure, and diabetic ketoacidosis. Rapid breathing in children or infants, especially with nostril flaring, belly breathing, or skin pulling in between the ribs, warrants immediate medical attention.

ICD-10: R06

A rapid heartbeat (tachycardia) means your heart beats faster than 100 times per minute at rest. Common non-emergency causes include exercise, fever, anxiety, caffeine, alcohol, or dehydration. Medical causes include anemia, hyperthyroidism, infections, and heart rhythm problems such as atrial fibrillation or supraventricular tachycardia (SVT). A sudden, unexplained racing heart — especially with chest pain, shortness of breath, fainting, or severe lightheadedness — is a medical emergency: call 911. If rapid heartbeat occurs frequently at rest or lasts more than a few minutes without a clear reason, notify your doctor. An ECG (electrocardiogram) can help identify the cause.

ICD-10: R00

A rapid response team (RRT) is a group of experienced hospital clinicians—usually including a critical care nurse, a respiratory therapist, and sometimes a physician—who respond quickly to early signs of deterioration in a hospitalized patient before a full emergency such as cardiac arrest occurs. Families and nurses can call the rapid response team if they notice a patient is suddenly breathing differently, becoming confused, or changing in color or consciousness. Most hospitals encourage patients and families to activate the RRT themselves if they are worried. Acting early can prevent a Code Blue and lead to better outcomes.

A rapid strep test detects group A Streptococcus bacteria in the throat in about five to ten minutes. A healthcare provider uses a sterile swab to wipe the back of your throat and tonsils. The swab is placed in a chemical solution that produces a colored line if strep bacteria are present, similar to a home pregnancy test strip. A positive result means you likely have strep throat and need antibiotics to prevent complications such as rheumatic fever. A negative result does not completely rule out strep, so many clinics send a follow-up throat culture to confirm. The test is quick and causes only brief gagging but no real pain.

A rash is a change in the skin's color, texture, or appearance. It may appear as redness, bumps, blisters, scales, or patches. Rashes have many causes, including allergic reactions, infections such as chickenpox or Lyme disease, contact with irritants, autoimmune diseases, and medication side effects. Some rashes are harmless and clear up on their own; others require treatment. Seek care right away if a rash spreads rapidly, covers a large area, is accompanied by fever, affects the face or genitals, or is painful and blistering, as these may indicate a serious condition.

ICD-10: R21

In the ACA context, reconciliation is the process of settling the difference between the advance premium tax credits (APTC) you received during the year and the amount you were actually entitled to based on your final income. You complete this on IRS Form 8962 when you file your federal tax return. If your income was lower than estimated, you may receive an additional refund. If your income was higher, you may owe some or all of the advance credits back. Updating your income estimate during the year at the marketplace can reduce the chance of owing a large repayment at tax time.

The recovery room, also called the Post-Anesthesia Care Unit (PACU), is where patients are monitored closely after surgery or a procedure requiring anesthesia. Nurses in the PACU watch your vital signs, pain level, and level of consciousness as the anesthesia wears off. You may feel groggy, nauseous, or cold. Family members are usually not allowed in the PACU initially, but a nurse will provide updates. Once you are stable, awake, and breathing well, you will be moved to a regular hospital room or discharged home. The length of time in the recovery room varies based on the surgery and your individual response to anesthesia.

Rectal bleeding refers to blood that exits the body through the rectum. It usually appears as bright red blood in the toilet bowl, on stool, or on toilet paper. The most common causes are hemorrhoids and anal fissures, which are generally benign. However, rectal bleeding can also indicate colon polyps, colorectal cancer, inflammatory bowel disease, or diverticular disease. Any new rectal bleeding in a person over 45 should be evaluated with colonoscopy. Rectal bleeding accompanied by dizziness, significant pain, large amounts of blood, or other concerning symptoms requires urgent or emergency medical attention.

ICD-10: K92

The rectum is the final five to six inches of the large intestine, connecting the sigmoid colon to the anal canal. It stores stool until the body is ready to have a bowel movement. Stretch receptors in the rectal wall sense when stool has filled the rectum and send a signal that creates the urge to defecate. Common conditions of the rectum include hemorrhoids — swollen veins in or around the rectum and anus — rectal bleeding, rectal cancer, and rectal prolapse, where the rectum slides out of place. Doctors examine the rectum with a digital rectal exam, a sigmoidoscopy, or a colonoscopy to check for abnormalities.

Red blood cells are the most common type of blood cell in the body. Their main job is to carry oxygen from the lungs to every organ and tissue, and to bring carbon dioxide back to the lungs to be exhaled. They get their red color from hemoglobin, a protein that binds to oxygen. Red blood cells are made in the bone marrow and live for about 120 days before being replaced. A low red blood cell count is called anemia, which can cause fatigue, weakness, and shortness of breath. Conditions like iron deficiency, vitamin B12 deficiency, and chronic kidney disease can reduce production of red blood cells.

Redetermination is the periodic process—usually annual—by which Medicaid reviews your eligibility to confirm you still qualify for coverage. States must notify you before your review date and attempt to renew coverage automatically using information already on file. If they cannot confirm eligibility without your input, they must contact you and give you time to provide updated information. During the post-COVID unwinding period, millions were disenrolled when states resumed redeterminations after a pause of several years. If you receive a redetermination notice, respond promptly to avoid losing coverage.

A reference product is the original FDA-approved biologic drug against which a biosimilar is evaluated for approval. Biologics are complex medicines derived from living cells—such as insulin analogs, monoclonal antibodies, and certain vaccines. When a manufacturer seeks to produce a biosimilar, the FDA requires clinical evidence demonstrating it is highly similar to the reference product with no clinically meaningful differences. Knowing which reference product a biosimilar was approved against confirms both are FDA-sanctioned options. Biosimilars typically cost less than the reference product, which can reduce your prescription costs.

A referral is a formal recommendation or authorization from your primary care provider (PCP) to see a specialist or receive a specific service. HMO plans generally require a referral for specialist visits to be covered; PPO plans often do not. A referral typically contains patient information, the reason for the visit, and relevant clinical history. Without a required referral, the specialist visit may not be covered by insurance, leaving the patient responsible for the full cost.

Referred pain is pain that is felt in a part of the body other than the actual source of the problem. This happens because nerves from different areas share pathways in the spinal cord, causing the brain to misinterpret where the pain signal originates. A classic example is heart attack pain felt in the left arm or jaw. A diaphragm problem may cause shoulder tip pain. Gallbladder issues can cause right shoulder pain. Referred pain can make diagnosis challenging, so providing your doctor with a complete description of all your symptoms and their locations—not just the most painful area—is important for accurate evaluation.

A refill is when your pharmacy dispenses an additional supply of a medication after your original prescription supply is used up. Your prescriber writes the number of allowed refills on your prescription. For most non-controlled medications, you can request refills without seeing your doctor again until all authorized refills are exhausted. Controlled substances often have no refills allowed or require a brand-new prescription each time. Your insurance plan may also restrict how early you can refill, typically not until you have used 75 to 80 percent of your current supply. Call or submit refill requests ahead of time to avoid running out.

A remark code is an alphanumeric code that appears on an Explanation of Benefits or remittance advice to provide additional information about how a claim was processed. Unlike denial codes, remark codes do not always mean a claim was rejected—they may explain payment adjustments, indicate a service was covered at a different rate, or clarify coordination of benefits decisions. Remark codes are standardized by CMS and begin with prefixes such as M, N, or MA. If you see an unfamiliar remark code on your EOB, look up its meaning on the CMS Remittance Advice Remark Code list or call your insurer.

A remittance advice (RA) is a document sent from an insurance payer to a healthcare provider that explains how a claim was processed and paid. It lists the services billed, the allowed amounts, what the plan paid, any adjustments made, denial reasons, and what — if anything — the patient owes. The Medicare version is called an Electronic Remittance Advice (ERA) or Standard Paper Remittance (SPR). While patients typically receive an Explanation of Benefits (EOB) with similar information, the remittance advice is primarily sent to providers for their billing records. Understanding remittance advice helps if you receive a balance bill that conflicts with what your insurer paid.

The renal arteries are a pair of blood vessels — one for each kidney — that branch off the aorta and carry oxygen-rich blood to the kidneys. Each kidney receives about twenty percent of the heart's output with every beat so it can filter the blood and produce urine. When a renal artery becomes narrowed — a condition called renal artery stenosis, usually caused by the buildup of plaque — blood flow to the kidney decreases, which can cause difficult-to-control high blood pressure and reduced kidney function. Doctors can diagnose this with imaging and sometimes treat it by widening the artery with a balloon and placing a stent to keep it open.

Research costs are expenses unique to a clinical trial that the study sponsor—typically a pharmaceutical or device company—is expected to pay. These include the investigational drug or device itself, extra lab tests or imaging required solely by the study protocol, and additional clinic visits that would not occur in standard care. Research costs differ from routine care costs. Under federal law, Medicare, Medicaid, and most private insurers must cover routine care costs for clinical trial participants but are not required to cover research costs. Your informed consent document should clearly identify which costs the sponsor bears and which your insurance may cover.

Respiratory failure occurs when the lungs cannot maintain adequate levels of oxygen in the blood, or cannot remove enough carbon dioxide. It is a serious condition that can result from severe pneumonia, COPD exacerbation, COVID-19, drug overdose, or trauma. There are two types: hypoxemic failure with low blood oxygen, and hypercapnic failure with elevated carbon dioxide. Symptoms include extreme shortness of breath, rapid breathing, confusion, and bluish skin. Treatment requires urgent medical care including supplemental oxygen, mechanical ventilation, and addressing the underlying cause. Respiratory failure is frequently managed in an intensive care unit.

ICD-10: J96

Respiratory rate is the number of breaths a person takes per minute. In hospitals, nurses count breaths by watching the chest rise, or monitoring equipment measures it automatically. Normal adult respiratory rate is 12 to 20 breaths per minute. A rate below 12 (bradypnea) may indicate drug overdose or neurological problems. A rate above 20 (tachypnea) can signal infections, asthma, anxiety, or heart problems. A very high or very low respiratory rate is considered an emergency and may lead to oxygen therapy or mechanical ventilation. Changes in your breathing rate are important indicators of your overall health status.

Respiratory therapy is care provided by a licensed respiratory therapist to evaluate, treat, and manage patients with breathing disorders and cardiopulmonary conditions. It includes administering aerosol medications, operating mechanical ventilators, teaching patients to use inhalers and home oxygen equipment, performing pulmonary function tests, and supporting patients during respiratory emergencies. Respiratory therapists work in hospitals, ICUs, pulmonary clinics, and home care settings. They help manage conditions such as asthma, COPD, cystic fibrosis, and respiratory failure. Sessions may be brief or extended depending on the patient's condition and setting.

Restless leg syndrome (RLS) is a neurological condition causing an irresistible urge to move the legs, typically accompanied by uncomfortable sensations described as crawling, tingling, aching, or pulling. Symptoms worsen at night or when resting and are temporarily relieved by movement such as walking or stretching. RLS can severely disrupt sleep, leading to daytime fatigue. It may be related to low iron levels, kidney failure, pregnancy, or certain medications, or it may be inherited. Treatment includes iron supplementation if deficient, lifestyle changes, and medications such as dopaminergic agents or alpha-2 delta ligands.

ICD-10: G25

Restless legs syndrome (RLS) is an irresistible urge to move the legs, usually accompanied by uncomfortable crawling, tingling, or burning sensations deep inside the limbs. Symptoms are typically worse at rest and in the evening or at night, and are temporarily relieved by movement. RLS disrupts sleep and can significantly reduce quality of life. Common causes and risk factors include iron deficiency, kidney disease, pregnancy, peripheral neuropathy, and genetics. Certain medications including some antidepressants and antihistamines can trigger or worsen RLS. It is a recognized neurological condition. Tell your doctor about symptoms, including timing and effect on sleep, for proper diagnosis and treatment.

ICD-10: G25

The retina is a thin layer of light-sensitive tissue lining the inside back of your eye. It works like the film in a camera. When light enters your eye and hits the retina, specialized cells called rods and cones convert it into electrical signals. These signals travel through the optic nerve to your brain, which interprets them as images. The central part of the retina, called the macula, is responsible for sharp, detailed vision. Conditions such as diabetic retinopathy, macular degeneration, and retinal detachment can seriously damage vision. A detached retina is a medical emergency — if the retina peels away from the back of the eye without prompt treatment, permanent vision loss can occur.

Retinal detachment is a medical emergency in which the retina, the light-sensitive tissue at the back of the eye, separates from its supporting tissue. Without prompt treatment, permanent vision loss can occur. Warning signs include a sudden increase in floaters, flashes of light, or a curtain-like shadow over part of your vision. Risk factors include severe nearsightedness, previous eye surgery, and family history. Treatment requires surgery and is most successful when performed quickly. After treatment, most patients regain useful vision, especially if the detachment did not involve the macula.

ICD-10: H33

Retroactive coverage means your health insurance starts on a date before your enrollment was formally approved. This commonly occurs with Medicaid—if you apply and are found eligible, your coverage may be backdated up to three months before your application date, covering services already received during that period. Retroactive coverage can eliminate or significantly reduce bills you incurred while waiting for approval. However, insurers and providers must be notified of the retroactive effective date so they can reprocess previously denied or unpaid claims within the plan's timely filing window.

Retrospective review is a type of utilization review conducted by an insurer after a medical service has already been provided. The insurer evaluates whether the completed care was medically necessary and appropriate. This review commonly applies to emergency services, services provided when prior authorization could not be obtained in advance, or when verifying that care met the plan's clinical criteria. If the retrospective review determines care was not medically necessary, the insurer may deny payment for all or part of the claim. Providers and patients typically have the right to appeal a denial that results from a retrospective review decision.

Rheumatoid arthritis is an autoimmune disease where the body's immune system mistakenly attacks the lining of the joints, causing chronic inflammation, pain, and swelling. Unlike osteoarthritis, it often affects joints symmetrically—both wrists, both knees—and can occur at any age. Over time it can damage cartilage and bone, leading to joint deformity. Fatigue and morning stiffness lasting over an hour are common. Treatment includes disease-modifying antirheumatic drugs (DMARDs), biologics, and physical therapy to slow joint damage and preserve function.

ICD-10: M05

The rib cage is the bony structure that surrounds and protects the heart, lungs, and other organs in the chest. It is made up of twelve pairs of curved ribs that attach to the spine at the back and, for the upper ten pairs, connect to the sternum at the front through cartilage. The lower two pairs — the floating ribs — do not attach to the sternum. Together the ribs form a protective cage around the vital chest organs. Rib fractures are common injuries from falls, car accidents, or chest trauma. Because the ribs move with every breath, a broken rib is very painful and can make breathing and coughing difficult. Multiple broken ribs can sometimes puncture a lung.

Under HIPAA, the right of access gives you the legal right to inspect and obtain copies of your own medical records and other protected health information held by a covered healthcare provider or health plan. Providers must respond within 30 days—or 60 days in certain circumstances—and can charge only a reasonable, cost-based fee. They cannot require you to explain why you want your records or make access unnecessarily burdensome. You can request records in electronic format if available. If a provider refuses, you may file a complaint with the HHS Office for Civil Rights.

Rosacea is a chronic skin condition that primarily affects the face, causing redness, visible blood vessels, and sometimes acne-like bumps. It most commonly affects fair-skinned adults between 30 and 60. The exact cause is unknown, but triggers include sun exposure, spicy foods, alcohol, stress, and hot beverages. Rosacea is not contagious and cannot be cured, but symptoms can be managed with topical medications, oral antibiotics, and laser therapy. Without treatment, rosacea may worsen over time. In severe cases, it can cause thickening of the skin on the nose, known as rhinophyma.

ICD-10: L71

The rotator cuff is a group of four muscles and their tendons that surround and stabilize the shoulder joint. These muscles hold the ball of the upper arm bone firmly in the shoulder socket and allow you to lift and rotate your arm. Rotator cuff injuries are very common, especially in people who do repetitive overhead motions — like athletes, painters, or construction workers. Injuries range from inflammation and tendinitis to partial or complete tears. Symptoms include shoulder pain, weakness, and difficulty lifting the arm. Treatment may include physical therapy, steroid injections, or surgery, depending on the severity of the injury.

A rotator cuff tear is a partial or complete tear of one or more of the four tendons that stabilize the shoulder joint and enable arm movement. It can result from a sudden injury—such as falling on an outstretched arm—or from gradual wear over time, especially in older adults and overhead workers. Symptoms include deep shoulder pain, weakness, limited range of motion, and pain that worsens at night. Treatment depends on tear size and severity: physical therapy, anti-inflammatory medications, and cortisone injections for partial tears, and arthroscopic surgery for complete or non-responsive tears.

ICD-10: M75

Routine care costs are the ordinary medical expenses a clinical trial participant would incur even without participating in the trial—such as doctor visit fees, standard lab work, imaging, and hospital stays required for their condition. Federal law and most state laws require Medicare, Medicaid, and private insurers to cover these costs for participants in qualifying clinical trials. The study sponsor covers expenses unique to the research; your insurance covers the care you would need regardless. If your insurer refuses to pay routine care costs for a clinical trial, you have the right to appeal that decision.

RSV (Respiratory Syncytial Virus) is a very common respiratory virus that infects almost all children by age 2. In most older children and adults it causes mild cold-like symptoms. However, in infants — especially those under 6 months or born prematurely — RSV can cause bronchiolitis, a serious lower airway infection with rapid breathing, wheezing, and low oxygen levels that may require hospitalization. RSV season runs from fall through spring in the US. In 2023, the FDA approved the first RSV vaccines for pregnant people and older adults, and nirsevimab (Beyfortus) is now recommended for most infants to prevent severe RSV illness.

ICD-10: J21

A rural health clinic (RHC) is a federally certified outpatient clinic in a rural, medically underserved area that receives enhanced Medicare and Medicaid reimbursement to improve access to care. RHCs must provide primary and preventive care services and employ a physician assistant, nurse practitioner, or certified nurse midwife at least 50 percent of the time. Services at an RHC are generally billed under a cost-based fee structure different from a standard doctor's office. RHCs may also serve as approved originating sites for Medicare-covered telehealth visits, expanding access for rural patients.

The Ryan Haight Online Pharmacy Consumer Protection Act of 2008 prohibits providers from prescribing controlled substances—such as opioids, stimulants, or benzodiazepines—via the internet or telehealth without first conducting an in-person medical evaluation. The law was named after Ryan Haight, who died after obtaining prescription drugs online illegally. During the COVID-19 pandemic, the DEA issued emergency waivers allowing controlled substance prescribing via telehealth without a prior in-person visit. The telemedicine exception continues these waivers under specific DEA conditions. Whether your telehealth provider can prescribe a controlled substance depends on which medications are covered and current DEA rules.

The sacrum is a large, triangular bone at the very base of your spine. It sits between the two hip bones and forms the back wall of the pelvis. The sacrum is actually made up of five vertebrae that fuse together during childhood. It connects the spine to the pelvis and helps distribute the weight of your upper body. At its lower end, it attaches to the tailbone (coccyx). The joints where the sacrum meets the hip bones are called the sacroiliac joints, which can be a source of lower back pain. Fractures of the sacrum can occur from falls or high-impact injuries.

The salivary glands are organs that produce saliva, the clear liquid that keeps your mouth moist, begins digesting food, and helps protect teeth from decay. There are three pairs of major salivary glands: the parotid glands (the largest, located in front of and below each ear), the submandibular glands (under the jaw), and the sublingual glands (under the tongue). Hundreds of tiny minor salivary glands are also scattered throughout the mouth. Saliva contains enzymes that break down starches, antibodies that fight bacteria, and proteins that lubricate the mouth and throat. When salivary glands become blocked by stones, infected, or affected by diseases like Sjogren's syndrome or cancer, they can become swollen and painful.

The scapula, commonly called the shoulder blade, is a flat, triangular bone located on the upper back on each side of your body. It connects the upper arm bone (humerus) and the collarbone (clavicle) and serves as an anchor point for many muscles of the shoulder, upper back, and arm. The scapula moves freely to allow a wide range of shoulder motion, including lifting, reaching, and rotating the arm. Fractures of the scapula are relatively rare and usually result from high-energy trauma. Winging of the scapula — where it sticks out from the back — can occur if certain nerves or muscles are damaged. Shoulder pain and stiffness often involve the scapula and surrounding muscles.

Schizophrenia is a serious but treatable mental health condition that affects how a person thinks, feels, and perceives reality. Symptoms may include hallucinations (hearing or seeing things others do not), delusions (strongly held false beliefs), disorganized thinking, and reduced emotional expression or motivation. Symptoms usually appear in late teens to early thirties. With proper treatment — including antipsychotic medications and supportive therapy — many people with schizophrenia lead meaningful, productive lives. Early intervention leads to better outcomes. Care is typically provided by a psychiatrist and a multidisciplinary mental health team. Community mental health centers across the US offer specialized services for people and families managing schizophrenia.

ICD-10: F20

Sciatica is pain that travels along the path of the sciatic nerve, which runs from the lower back through the buttocks and down each leg. The pain usually affects only one side of the body and may feel like a sharp electric shock, burning, or aching that radiates from the lower back into the leg and sometimes into the foot. It is often caused by a herniated disc or bone spur pressing on the nerve. Numbness, tingling, or muscle weakness in the affected leg is also common. Most cases improve within weeks to months with physical therapy and anti-inflammatory medications. Surgery may be considered if symptoms are severe or persistent.

ICD-10: M54

Sciatica refers to pain that radiates along the path of the sciatic nerve, which runs from the lower back through the hips and buttocks and down each leg. It is typically caused by a herniated disc, bone spur, or narrowing of the spine compressing part of the nerve. The pain can range from a mild ache to a sharp, burning sensation or electric shock—usually affecting one side of the body. Numbness and tingling in the leg or foot are common. Most sciatica resolves with physical therapy, anti-inflammatory medications, and time, though severe cases may require injections or surgery.

ICD-10: M54

The sclera is the tough, white outer covering of your eyeball — the part you see as the whites of the eyes. It is a thick, fibrous tissue that gives the eye its shape and protects the delicate inner structures. The sclera covers about 80 percent of the eyeball's surface and is continuous with the cornea at the front. It provides attachment points for the six muscles that move the eye. When blood vessels in the overlying conjunctiva (a clear membrane covering the sclera) become irritated or broken, the whites of the eyes turn red. A condition called scleritis is painful inflammation of the sclera itself, sometimes linked to rheumatoid arthritis. Yellowing of the sclera is a sign of jaundice, indicating liver problems.

Scoliosis is an abnormal lateral curvature of the spine, often appearing as an S or C shape when viewed from the back. It most commonly develops during the growth spurt just before puberty, though it can occur at any age and from various causes including neuromuscular conditions or birth defects. Mild scoliosis may cause no symptoms, while moderate to severe curves can cause back pain, uneven shoulders or hips, and in severe cases, reduced lung function. Treatment depends on severity and includes observation, back bracing during growth, and surgery for curves that progress significantly.

ICD-10: M41

Secondary insurance is a health insurance plan that pays after your primary insurance has processed a claim. When you have two health plans — for example, your own employer plan and coverage through a spouse — they coordinate benefits so that together they may cover more of your costs than either plan alone. The secondary plan typically covers some or all of what the primary plan did not pay, including deductibles, copays, and coinsurance. Coordination of benefits rules determine which plan pays first. Having secondary insurance does not mean all your costs are covered, but it can significantly reduce your out-of-pocket expenses. You must enroll in and actively use both plans.

Section 1557 of the Affordable Care Act prohibits discrimination in healthcare on the basis of race, color, national origin, sex, age, or disability in programs receiving federal funding. It requires covered healthcare entities to provide meaningful access for people with limited English proficiency, including free qualified interpreter services and translated written materials. Patients have the right to a competent medical interpreter at no cost; using family members as interpreters is discouraged for clinical encounters. Complaints can be filed with HHS Office for Civil Rights.

Sedation is the use of medication to help a patient relax, feel drowsy, or sleep lightly during a medical procedure without full general anesthesia. It ranges from minimal sedation, where patients are relaxed but fully awake, to moderate or deep sedation, where they may not remember the procedure afterward. It is commonly used for colonoscopies, endoscopies, dental procedures, biopsies, and minor surgeries. Medications such as midazolam, propofol, or fentanyl are used depending on the level needed. A clinician monitors breathing and vital signs throughout. You will need someone to drive you home after moderate or deep sedation. Grogginess and mild confusion are common immediately after sedation and typically resolve within a few hours.

A seizure is a sudden burst of abnormal electrical activity in the brain that may cause uncontrolled shaking, stiffening, confusion, loss of consciousness, or staring spells. Causes include epilepsy, high fever, low blood sugar, stroke, head injury, and drug withdrawal. Call 911 immediately for a first-time seizure, a seizure lasting more than five minutes, a person who does not wake up afterward, injury during a seizure, or seizures in a pregnant person or someone with diabetes. Do not restrain the person or put anything in their mouth. Cushion their head and stay with them until help arrives.

ICD-10: R56

Self-pay refers to a patient who does not have health insurance or who chooses to pay for a medical service out of pocket rather than through insurance. Self-pay patients are often initially billed at the chargemaster rate—the hospital's highest list price—though most facilities offer self-pay discounts or sliding-fee scales. Federal law requires hospitals to screen self-pay patients for charity care eligibility before sending bills to collections. Always ask about the self-pay discount, available payment plans, or charity care programs before paying any bill in full, as the reduced price can be substantially lower than the original invoice.

Separate CHIP refers to a state Children's Health Insurance Program that operates independently from Medicaid, with its own eligibility rules, benefit packages, and cost-sharing requirements. States may structure CHIP as a Medicaid expansion or as a separate standalone program. Children in a separate CHIP program may have different covered services, copayments, or premium requirements compared to children in Medicaid. Understanding which type of CHIP your child is enrolled in matters when comparing benefits, choosing a doctor, or applying for additional financial assistance programs.

Sepsis is a life-threatening medical emergency that occurs when the body's response to an infection becomes extreme and starts to damage its own tissues and organs. It can develop from any infection, including pneumonia, UTIs, or skin infections. Symptoms include high fever or very low temperature, rapid heart rate, rapid breathing, confusion, and extreme fatigue. Sepsis can progress to septic shock with dangerously low blood pressure and organ failure. Treatment requires immediate hospitalization with intravenous antibiotics, fluids, and sometimes medications to raise blood pressure. Early recognition and rapid treatment are critical to survival and recovery.

ICD-10: A41

Sexually transmitted infections (STIs) are infections spread primarily through sexual contact. Common STIs include chlamydia, gonorrhea, syphilis, herpes, HPV, and HIV. Many STIs have no symptoms, making routine screening essential for sexually active individuals. Untreated STIs can lead to serious complications including infertility, chronic pain, increased cancer risk, and transmission to others including newborns. Treatment depends on the specific infection — bacterial STIs like chlamydia and gonorrhea are curable with antibiotics, while viral infections like herpes and HIV are manageable but not curable. Condoms and vaccines (HPV, hepatitis B) help prevent transmission.

ICD-10: A64

Sharp pain is an intense, piercing, or stabbing type of pain that typically comes on suddenly and is felt at a specific point. It is often brief but may recur in waves. Sharp pain can signal tissue injury, inflammation, or nerve irritation. Common causes include muscle tears, kidney stones passing through the ureter, appendicitis, pleurisy (inflammation around the lung), gallbladder problems, or a pinched nerve. This type of pain is the body's urgent signal that something may be seriously wrong. Seek immediate care if sharp pain is severe, sudden, occurs in the chest or abdomen, or is accompanied by other alarming symptoms such as fever, vomiting, or sweating.

Shortness of breath, also called dyspnea, is the feeling that you cannot breathe in enough air or that breathing takes extra effort. It may come on suddenly or develop slowly over time. Common causes include asthma, COPD, heart failure, anemia, anxiety, and lung infections like pneumonia. Mild breathlessness after exercise can be normal, but shortness of breath at rest, when lying flat, or accompanied by chest pain, dizziness, or blue lips requires immediate emergency care. Tell your doctor how long it has lasted and what makes it better or worse.

ICD-10: R06

Shoulder pain is discomfort in or around the shoulder joint, which is one of the most mobile joints in the body. It may feel like aching, sharp stabbing, or a burning sensation. Common causes include rotator cuff tears or tendinitis, bursitis, frozen shoulder (adhesive capsulitis), arthritis, or dislocation. Shoulder pain can also be referred from the neck or heart. Treatment may include rest, ice, physical therapy, anti-inflammatory medications, or in some cases surgery. See a provider if the pain is severe, follows an injury, limits arm movement, or is accompanied by chest pain, which may indicate a heart problem.

ICD-10: M75

Sickle cell disease is an inherited blood disorder in which red blood cells form an abnormal crescent or sickle shape instead of the normal round shape. These misshapen cells become rigid, sticky, and prone to breaking apart. They can block small blood vessels, causing severe pain episodes called crises, organ damage, and anemia. The disease primarily affects people of African, Mediterranean, Middle Eastern, and South Asian descent. Symptoms begin in early childhood and include pain episodes, frequent infections, delayed growth, and vision problems. Treatment includes medications to manage pain, prevent complications, and in some cases bone marrow transplant or gene therapy.

ICD-10: D57

SIDS is the sudden, unexplained death of an apparently healthy baby under one year of age, usually during sleep. It is the leading cause of death for babies 1 to 12 months old in the US. The exact cause is unknown, but risk is reduced by following the ABCs of safe sleep: place baby Alone, on their Back, in a Crib or bassinet with a firm flat surface and no soft bedding, blankets, bumpers, or toys. Breastfeeding, using a pacifier, room-sharing (not bed-sharing), avoiding smoke exposure, and offering vaccines all lower risk. SIDS risk is highest between 2 and 4 months.

ICD-10: R95

The sigmoid colon is the S-shaped final section of the large intestine before it connects to the rectum. It sits in the lower left part of the abdomen and gets its name from the Greek letter sigma, which looks like an S. The sigmoid colon acts as a temporary holding area for stool before it moves into the rectum to be expelled. It is the most common site for diverticulitis — an infection or inflammation of small pouches called diverticula that form in the colon wall. It is also a frequent location for colon polyps and colon cancer. A sigmoidoscopy is a procedure that uses a small camera to look specifically at the sigmoid colon and rectum.

The sinuses are hollow, air-filled spaces inside the bones of your face and skull. There are four pairs of sinuses named by their location: frontal (behind the forehead), maxillary (in the cheekbones), ethmoid (between the eyes), and sphenoid (deep behind the nose). The sinuses are lined with a mucous membrane that produces mucus, which drains into the nasal cavity and helps filter air you breathe. They also make your voice resonate and reduce the weight of your skull. When the lining becomes inflamed and the drainage openings become blocked — usually due to a cold, allergies, or infection — you develop sinusitis, causing pressure, facial pain, and congestion.

A skilled nursing facility (SNF) is a licensed residential care facility providing around-the-clock nursing care and rehabilitative services—including physical therapy, occupational therapy, and speech therapy—for patients who need more care than can be provided at home but do not require acute hospitalization. Medicare Part A covers SNF care for up to 100 days per benefit period following a qualifying inpatient hospital stay of at least three days. Days 21–100 require a significant daily coinsurance. Medicaid may cover long-term SNF stays for eligible individuals. Ask your care team what happens to your coverage once Medicare SNF days run out.

A skin biopsy removes a small sample of skin tissue so a pathologist can examine it under a microscope. It is performed to diagnose skin cancers (such as melanoma, basal cell, or squamous cell carcinoma), rashes, infections, or other skin diseases. The most common technique is a punch biopsy, where a circular blade removes a cylinder of skin; a shave biopsy uses a blade to shave off a thin layer. The area is numbed with a local anesthetic injection, which may sting briefly. You may need one or two stitches afterward. Results are usually available within a week. The procedure is performed by a dermatologist or primary care doctor in an outpatient setting.

A skin graft is a surgical procedure in which healthy skin is removed from one area of the body (the donor site) and transplanted to cover a wound, burn, or area where skin has been lost. There are two main types: split-thickness grafts, which use the upper layers of skin, and full-thickness grafts, which include all layers. Skin grafts are used to treat severe burns, large wounds, areas where skin has been surgically removed due to cancer, and chronic ulcers. The procedure is done under general or local anesthesia. The grafted skin must be kept moist and protected until it adheres and receives blood supply, typically within five to seven days. Both the donor and graft sites require careful wound care during recovery.

A skin lesion is any abnormal area of skin that looks different from the surrounding skin. Lesions include moles, warts, blisters, scales, ulcers, sores, and abnormal growths. They may be benign or potentially cancerous. Warning signs that a mole or growth may be melanoma include asymmetry, irregular borders, multiple colors, a diameter larger than a pencil eraser, or changes in size or appearance. Sores that do not heal, new growths, or skin changes that last more than a few weeks should be evaluated by a dermatologist. Early detection of skin cancer greatly improves outcomes.

The skull is the hard, bony shell that surrounds and protects your brain. It is made up of several flat bones that fuse together during childhood. The skull also forms the structure of your face and holds your eyes, nose, and jaw in place. At its base, it connects to the top of your spine, allowing your head to turn and tilt. Doctors examine the skull using X-rays or CT scans after head injuries, falls, or accidents. A fracture means one of these bones has cracked. During brain surgeries, part of the skull may be temporarily removed and later replaced.

The Second Lowest Cost Silver Plan (SLCSP) is the marketplace benchmark plan used to calculate the maximum premium tax credit you are eligible to receive. The IRS and marketplace use the SLCSP premium for your area, age, and household size when determining your advance premium tax credit. This figure appears in column B of IRS Form 1095-A, which you receive after enrolling in marketplace coverage. You must use the SLCSP amount when completing Form 8962 to reconcile your premium tax credit on your federal tax return. If column B on your 1095-A is blank or shows zero, use the HealthCare.gov SLCSP lookup tool.

Sleep apnea is a condition in which breathing repeatedly stops and starts during sleep. The most common type, obstructive sleep apnea, occurs when the throat muscles relax and block the airway. Symptoms include loud snoring, gasping or choking during sleep, excessive daytime sleepiness, morning headaches, and difficulty concentrating. Untreated sleep apnea increases the risk of high blood pressure, heart disease, and diabetes. Diagnosis is made with a sleep study. The most effective treatment is continuous positive airway pressure, or CPAP, which keeps the airway open. Lifestyle changes such as weight loss and avoiding alcohol can also help.

ICD-10: G47

Sleep apnea symptoms include loud snoring, gasping or choking during sleep, waking up frequently during the night, morning headaches, dry mouth on waking, excessive daytime sleepiness despite a full night of sleep, and difficulty concentrating. A bed partner may notice pauses in your breathing during the night. Untreated sleep apnea raises the risk of high blood pressure, heart disease, stroke, and diabetes. If you or a family member notices these patterns, speak with your doctor. Diagnosis typically requires a sleep study. Many people find significant relief with CPAP therapy or other treatments.

ICD-10: G47

A sleep study records your body's functions while you sleep to diagnose sleep disorders such as sleep apnea, insomnia, or narcolepsy. You will spend the night at a sleep center where sensors are attached to your scalp, face, chest, and legs to monitor brain waves, eye movements, heart rate, oxygen levels, airflow, and body movements. The sensors are attached with a mild paste and are not painful. A technician monitors you from another room. You should bring comfortable pajamas and any medications you normally take. An at-home sleep test is a simpler alternative sometimes used to diagnose sleep apnea. Results are usually available within one to two weeks after a sleep specialist reviews the data.

A sliding fee scale is a payment structure that adjusts the cost of healthcare services based on the patient's income and family size. Federally Qualified Health Centers (FQHCs) are required by law to offer sliding fee discounts to all patients regardless of insurance status. Fees are calculated as a percentage of the federal poverty level: patients at or below 100% FPL pay minimal or no fees, while those with higher incomes pay on a graduated scale up to the full charge. Documentation of income is required.

A slow heartbeat (bradycardia) means the heart beats fewer than 60 times per minute at rest. In well-trained athletes this is normal and healthy. In others, it may cause fatigue, dizziness, shortness of breath, near-fainting, or confusion. Causes include hypothyroidism, electrolyte imbalances, heart block, sick sinus syndrome, and certain medications such as beta-blockers and digoxin. Call 911 if bradycardia is associated with fainting, chest pain, or difficulty breathing. Mild bradycardia without symptoms may only need monitoring. Your doctor may order an ECG, Holter monitor, or blood tests to find the cause and determine if a pacemaker is needed.

ICD-10: R00

Slurred speech (dysarthria) means speaking in a thick, mumbled, or slow way that is difficult for others to understand. The muscles controlling speech may be weak or poorly coordinated. Common causes include alcohol intoxication, sedating medications, stroke, Parkinson's disease, multiple sclerosis, and brain tumors. Sudden slurred speech — especially combined with facial drooping, arm weakness, severe headache, or vision changes — is a medical emergency and a key stroke warning sign. Call 911 immediately. Do not wait to see if it improves on its own. If slurred speech develops gradually over weeks, schedule a prompt appointment with your doctor for evaluation.

ICD-10: R47

The small intestine is a long, coiled tube — about twenty feet in adults — that fills most of the middle of the abdomen. Despite its name, it is actually longer than the large intestine; it is called small because of its narrower diameter. This is where most digestion and nearly all nutrient absorption takes place. The inner walls are covered with millions of tiny finger-like projections called villi that greatly increase the surface area for absorbing nutrients into the bloodstream. The small intestine has three sections: the duodenum, the jejunum, and the ileum. Conditions like Crohn's disease, celiac disease, and bowel obstructions commonly affect the small intestine.

Sneezing is a reflex that forcefully expels air through the nose and mouth to clear irritants from the nasal passages. Occasional sneezing is completely normal. Frequent or prolonged sneezing is most commonly caused by allergic rhinitis (hay fever), the common cold, influenza, or other upper respiratory infections. Less commonly it can result from nasal polyps, exposure to cold air or bright light, or irritants such as dust, smoke, or chemical fumes. Sneezing that is persistent, accompanied by thick nasal discharge, fever, facial pressure, or loss of smell warrants evaluation to distinguish allergies from a sinus infection or other condition.

ICD-10: R06

Social anxiety disorder is an intense, persistent fear of being watched, judged, or embarrassed in social or performance situations. It goes well beyond shyness — it can cause people to avoid school, work, social events, or any situation where they might interact with others. Physical symptoms can include blushing, sweating, trembling, racing heart, nausea, and difficulty speaking. The fear is recognized as excessive but feels very real and difficult to control. Social anxiety disorder is one of the most common anxiety conditions in the US and is very responsive to treatment. Cognitive behavioral therapy (CBT) and certain medications, such as SSRIs, are effective first-line treatments. Many people experience significant improvement with proper care.

ICD-10: F40

A sore throat is pain, scratchiness, or irritation in the throat that often gets worse when you swallow. Most sore throats are caused by viral infections like the common cold or flu and go away on their own within a week. Other causes include strep throat (a bacterial infection), allergies, dry air, acid reflux, or irritants. Gargling with warm salt water, throat lozenges, and drinking fluids can help ease the discomfort. See a provider if the sore throat is very severe, lasts more than a week, comes with a high fever, difficulty swallowing or breathing, drooling, or swollen lymph nodes in the neck.

A Special Enrollment Period (SEP) is a window outside of the annual open enrollment period during which individuals can enroll in or change health insurance due to a qualifying life event. Qualifying events include losing other coverage (job loss, end of COBRA), getting married or divorced, having a baby or adopting a child, moving to a new coverage area, or gaining citizenship. SEPs typically last 60 days from the qualifying event. Marketplace SEPs require documentation of the qualifying event.

A Special Enrollment Period (SEP) is a limited window—typically 60 days—outside the annual Open Enrollment Period during which you can enroll in or change a marketplace health insurance plan. SEPs are triggered by qualifying life events such as losing other health coverage, getting married, having a baby, moving to a new coverage area, or gaining citizenship. Medicaid and CHIP enrollment remain open year-round regardless of SEPs. If you miss your SEP window, you must wait until Open Enrollment unless another qualifying event occurs. Keep documentation of your qualifying event as the marketplace may request proof before activating your coverage.

A specialist is a physician with advanced training and board certification in a specific area of medicine, such as cardiology, oncology, orthopedics, or dermatology. Specialists focus on diagnosing and treating conditions within their area of expertise, often after referral from a primary care provider. Specialist visits typically carry higher copays than PCP visits. HMO plans usually require a referral; PPO plans typically allow direct access. Seeing an in-network specialist is critical for cost control.

A specialty pharmacy is a licensed pharmacy that dispenses complex, high-cost medications used to treat serious chronic conditions such as cancer, multiple sclerosis, rheumatoid arthritis, hepatitis C, or rare diseases. These pharmacies offer additional services beyond a typical retail pharmacy, including clinical monitoring, help with insurance prior authorizations, copay assistance programs, and home delivery. Many specialty drugs require special handling, storage such as refrigeration, or particular administration methods. Your insurer or doctor may require you to obtain specialty medications only from pharmacies in the plan's designated specialty network to ensure proper coverage and support.

Speech difficulty refers to trouble finding words, forming sentences, or expressing thoughts verbally. It may involve slow or halting speech, inability to recall the right words (aphasia), or speaking in confused or garbled phrases. Sudden onset of speech difficulty — especially combined with facial drooping, arm weakness, severe headache, or vision changes — is a medical emergency and a key stroke warning sign. Call 911 immediately. Other causes of speech difficulty include Parkinson's disease, dementia, ALS, brain tumors, and medication side effects. If speech difficulty develops gradually or intermittently, schedule an urgent evaluation with your doctor to identify and treat the underlying cause.

ICD-10: R47

Speech therapy, also called speech-language pathology, helps people improve communication skills and swallowing function. A licensed speech-language pathologist evaluates and treats difficulties with speaking, understanding language, reading, writing, voice quality, and safe swallowing. Sessions are individualized and may involve exercises, assistive devices, or strategies for communicating more clearly. Speech therapy is used after stroke, traumatic brain injury, surgery on the throat, or for developmental delays in children. The goal is to restore or build the best possible communication and swallowing abilities for everyday life.

Spina bifida is a birth defect occurring when the neural tube—the structure that becomes the brain and spinal cord—does not close completely during early pregnancy. This leaves part of the spinal cord exposed or covered with a sac. Severity varies: spina bifida occulta may cause no symptoms, while myelomeningocele (the most serious form) causes leg weakness or paralysis, bowel and bladder problems, and hydrocephalus. Adequate folic acid before and during early pregnancy significantly reduces risk. Treatment includes surgery after birth, and ongoing care with physical, occupational, and urological specialists throughout life.

ICD-10: Q05

Spinal fusion is surgery that permanently joins two or more vertebrae in the spine so they heal into a single solid bone. It is done to eliminate painful motion between vertebrae caused by conditions such as degenerative disc disease, scoliosis, spinal fractures, or instability. Bone graft material and hardware such as rods, screws, or plates may be used to hold the vertebrae in place while they fuse. The surgery is performed under general anesthesia and takes two to six hours depending on the number of levels fused. Recovery varies widely but typically involves a hospital stay of two to four days and a return to light activity in four to six weeks. Full fusion may take several months.

Spinal stenosis is a narrowing of the spinal canal that puts pressure on the spinal cord or nerve roots. It most often occurs in the lower back (lumbar) or neck (cervical) regions, usually due to age-related changes such as bone spurs, thickened ligaments, or herniated discs. Symptoms include pain, numbness, tingling, or weakness in the arms, legs, or buttocks, often worsened by standing and walking and relieved by sitting or bending forward. Treatment options range from physical therapy and epidural injections to surgical decompression for severe cases.

ICD-10: M48

Spirometry is a simple breathing test that measures how much air you can breathe in and out, and how fast you can exhale. You will sit comfortably and breathe into a mouthpiece connected to a device called a spirometer, while wearing a nose clip to prevent air from escaping. The technician will ask you to take a deep breath and then blow out as hard and fast as possible. You will repeat this three or more times to get consistent results. The test takes about 15 minutes. It is used to diagnose and monitor conditions such as asthma, COPD, and other lung diseases. Avoid smoking and heavy exercise for a few hours before the test.

The spleen is a fist-sized organ in the upper left part of the abdomen, tucked under the rib cage next to the stomach. It is the largest lymphatic organ in the body. The spleen filters blood, removing old or damaged red blood cells and helping fight infections by producing white blood cells and antibodies. It also acts as a reservoir for blood that can be released during blood loss. An enlarged spleen — called splenomegaly — can occur with infections like mono, liver disease, and blood disorders. Because the spleen is not essential for survival, it is sometimes surgically removed — a splenectomy — after trauma or disease. People without a spleen must take precautions to avoid certain infections.

Splinting is the application of a rigid or semi-rigid support — called a splint — to stabilize an injured limb, joint, or bone. Unlike a full cast, a splint does not encircle the limb completely, allowing for swelling that is common in acute injuries. Splints are often used as a first-line treatment for fractures, sprains, and joint injuries. They may be temporary until swelling goes down and a cast can be applied, or they may serve as the definitive treatment for stable fractures. Splints can be prefabricated or custom-made and are typically secured with elastic bandages.

Under the federal EMTALA law, stabilization is the required medical treatment a hospital emergency department must provide to prevent an emergency medical condition from materially deteriorating before or during a patient transfer. A condition is considered stabilized when the treating physician determines there is no reasonable expectation it will worsen with or without continued hospital care. Hospitals with specialized capabilities must also accept appropriate transfers of unstabilized patients. If a hospital discharges or transfers you before you are stabilized, it may be violating federal law, and you can file a complaint with CMS or your state health department.

A state medical board is the government agency in each U.S. state responsible for licensing physicians and other healthcare professionals, investigating complaints of professional misconduct, and taking disciplinary action when warranted. Boards can revoke, suspend, or restrict a provider's license, impose fines, and require remedial education. All licensed physicians must be in good standing with their state medical board. As a patient, you can look up a physician's license status and any disciplinary history on your state board's public database. If you have a concern about a provider's professional conduct—not a billing dispute—the state medical board is the appropriate agency to contact.

Statins are medications that lower LDL (bad) cholesterol by reducing the amount of cholesterol the liver makes. Lowering cholesterol helps reduce the risk of heart attack and stroke. Common statins include atorvastatin (Lipitor), simvastatin, and rosuvastatin (Crestor). They are usually taken once daily, often at bedtime. Most people tolerate statins well, but muscle aches are a known side effect — tell your doctor if you experience severe muscle pain or weakness. Avoid grapefruit juice with some statins, as it can increase side effects. Statins work best alongside a healthy diet low in saturated fat.

Step therapy, also called fail-first protocol, is an insurance cost-control practice requiring patients to try less expensive or generic medications or treatments before the insurer will cover a more costly or brand-name option. For example, your plan may require you to try and fail on two generic drugs before approving a brand-name biologic. If the first-step treatment does not work or causes side effects, you can request to move to the next step. Your doctor can request a step therapy exception if the required first-step treatment is medically inappropriate for you. Many states have laws protecting patients from unreasonable step therapy requirements.

A step therapy exception is a formal request asking your insurance plan to skip the step therapy requirement and approve the specific medication your doctor originally prescribed. Step therapy—also called fail-first policy—requires patients to try and fail on cheaper drugs before the insurer will approve a more expensive option the doctor recommended. An exception may be granted when prior trials of required drugs were unsuccessful, clinically contraindicated, or would cause serious adverse effects. Many states have laws requiring insurers to respond to step therapy exception requests within specific timeframes, including within 24 to 72 hours in urgent situations.

The sternum, commonly called the breastbone, is a long, flat bone in the center of the chest. It runs from just below the notch at the base of the throat down to the upper abdomen. The ribs attach to it on both sides through cartilage, forming the front of the rib cage that protects the heart and lungs. During cardiac surgery such as open-heart surgery or a coronary artery bypass, the surgeon must cut through the sternum — a procedure called a median sternotomy — to access the heart. After surgery the sternum is wired back together and takes several weeks to heal. Pain in the sternum can result from costochondritis — inflammation of the cartilage connecting the ribs to the sternum.

Stiffness is a feeling of tightness, reduced flexibility, or difficulty moving a joint or muscle, especially after rest or in the morning. It can be mild and temporary or persistent and limiting. Morning stiffness that improves after moving around for about 30 minutes is typical of osteoarthritis, while stiffness lasting more than an hour is more characteristic of rheumatoid arthritis or other inflammatory conditions. Stiffness can also result from muscle overuse, injury, fibromyalgia, or prolonged immobility. Gentle stretching, warm baths, and anti-inflammatory medications can help. Tell your provider how long the stiffness lasts each day and which parts of the body are affected.

The stomach is a muscular, J-shaped organ in the upper left part of the abdomen that receives food from the esophagus and begins the process of digestion. Its walls churn and mix food with stomach acid and digestive enzymes, breaking it down into a semi-liquid called chyme. The acid — hydrochloric acid — is strong enough to kill many bacteria that enter with food. The stomach can stretch to hold about one liter of food and liquid. After several hours, the partially digested food passes through a muscular opening at the stomach's lower end, called the pyloric valve, into the small intestine. Conditions such as ulcers, gastritis, and stomach cancer all affect the stomach.

A stool culture is a laboratory test that grows and identifies bacteria, parasites, or other pathogens in a sample of your bowel movements. You collect a small amount of stool in a sterile container provided by the clinic, typically catching it on a sheet of plastic placed over the toilet. The lab places the sample on growth plates and watches for two to three days to see what organisms grow. If bacteria such as Salmonella, Shigella, Campylobacter, or E. coli are found, lab staff also test which antibiotics can treat the infection. Doctors order stool cultures for persistent diarrhea, bloody stool, foodborne illness investigations, and traveler's diarrhea.

Strep throat is a bacterial infection of the throat and tonsils caused by group A Streptococcus bacteria. It is highly contagious and spreads through respiratory droplets when an infected person coughs or sneezes. Symptoms include sudden severe sore throat, pain when swallowing, fever, red and swollen tonsils sometimes with white patches or streaks of pus, swollen lymph nodes in the neck, and headache. It usually does not cause a cough. A rapid strep test or throat culture confirms the diagnosis. Treatment with antibiotics such as penicillin or amoxicillin clears the infection, prevents spread, and reduces the risk of complications such as rheumatic fever.

ICD-10: J02

A stroke happens when blood supply to part of the brain is cut off, either by a blocked artery (ischemic stroke) or a ruptured blood vessel (hemorrhagic stroke). Without blood, brain cells begin to die within minutes. Symptoms include sudden numbness or weakness on one side of the face or body, confusion, trouble speaking, vision problems, severe headache, and loss of balance. Remember the acronym FAST: Face drooping, Arm weakness, Speech difficulty, Time to call 911. Stroke is a medical emergency. Prompt treatment can limit brain damage and improve recovery outcomes.

ICD-10: I63

Stroke rehabilitation is a coordinated set of therapies designed to help stroke survivors regain lost abilities and adapt to any lasting impairments. It typically combines physical therapy to rebuild strength and coordination, occupational therapy to relearn daily tasks, and speech therapy to address communication or swallowing difficulties. Rehabilitation may begin in the hospital within days of the stroke and continue at a rehabilitation facility, outpatient clinic, or at home. Early and intensive rehabilitation improves recovery outcomes. The brain's ability to reorganize and form new connections — called neuroplasticity — is the foundation of stroke recovery.

The subcutaneous tissue, sometimes called the hypodermis, is the deepest layer of your skin. It sits below the dermis and is made up mainly of fat and loose connective tissue. This layer acts as a cushion to protect your internal organs and bones from impact, stores energy in the form of fat, and helps regulate body temperature by insulating the body. Blood vessels and nerves that supply the upper skin layers run through this tissue. When medications like insulin are injected under the skin, they go into this layer. Conditions such as lipomas (benign fat lumps) and cellulitis (bacterial infection) can develop in the subcutaneous tissue.

Substance use disorder is a medical condition in which a person's use of alcohol, drugs, or other substances causes significant health problems, distress, or impairs their ability to meet responsibilities at work, school, or home. It is not a moral failing — it is a chronic brain condition that responds to treatment. Symptoms include strong cravings, loss of control over use, withdrawal symptoms, and continued use despite negative consequences. Treatment may include behavioral therapy, support groups, and medication. In the US, the Substance Abuse and Mental Health Services Administration (SAMHSA) helpline at 1-800-662-4357 can connect you with local treatment resources confidentially at no cost.

ICD-10: F19

Suicide prevention refers to efforts and services designed to reduce suicidal thoughts and behaviors and to keep people safe. If you or someone you know is having thoughts of suicide, help is available. In the US, you can call or text 988 to reach the Suicide and Crisis Lifeline, available 24 hours a day, 7 days a week, in English and Spanish. The Crisis Text Line is also available by texting HOME to 741741. If there is immediate danger, call 911 or go to the nearest emergency room. Healthcare providers are trained to ask about suicidal thoughts without judgment, and discussing these thoughts is an important step toward getting the right support. You are not alone.

A summary of benefits is a brief overview document explaining what a health insurance plan covers, what you pay in premiums, deductibles, copays, and coinsurance, and which services are included or excluded. Medicare Advantage and Part D plans must send enrollees an Annual Notice of Change each fall that includes a summary of benefits for the upcoming year. While similar in name to the ACA-required Summary of Benefits and Coverage (SBC), the Medicare summary follows separate CMS formatting rules. Review your summary of benefits each year during open enrollment to check for changes in costs or covered services before deciding whether to stay in your plan.

The Summary of Benefits and Coverage (SBC) is a standardized, plain-language document that health insurers must provide to help you compare plans. It uses a uniform format required by the ACA and covers key information including deductibles, out-of-pocket maximums, copays, coinsurance, and what the plan covers or excludes. It also includes a coverage example showing estimated costs for common medical scenarios like having a baby or managing a chronic condition. You should receive an SBC when you enroll, at renewal, and upon request. Comparing SBCs across plans makes it easier to understand your total potential costs.

The Summary of Benefits and Coverage (SBC) is a standardized, plain-language document the ACA requires all health insurers to provide when you apply for, enroll in, or renew a health plan. The SBC uses a uniform template enabling side-by-side plan comparison. It includes the plan's deductible, out-of-pocket maximum, covered services, cost-sharing amounts, and two coverage examples showing how the plan handles a typical pregnancy and a simple fracture. A uniform glossary of insurance terms accompanies the SBC. By law you must receive the SBC before enrolling, and insurers must provide it within seven business days of your request.

A superbill is a detailed itemized receipt provided by a healthcare provider — most commonly therapists, out-of-network doctors, and chiropractors — that includes all the information your insurance company needs to process a reimbursement claim: patient and provider information, dates of service, diagnosis codes (ICD-10), procedure codes (CPT or HCPCS), and charges. You use a superbill to submit a claim yourself when your provider does not bill insurance directly. This is common with out-of-network providers or providers who do not accept your specific plan. Keep your superbill; it is your primary document for seeking reimbursement.

A surprise bill is an unexpected medical charge a patient receives when they receive care from an out-of-network provider without knowing it — for example, when an out-of-network anesthesiologist assists during an in-network surgery, or when a patient is taken to an out-of-network ER during an emergency. The No Surprises Act, effective January 2022, restricts surprise billing in emergency situations and for certain ancillary services, requiring providers to charge only in-network cost-sharing rates and prohibiting balance billing in covered situations.

Surprise billing occurs when you unknowingly receive care from an out-of-network provider — often in an emergency or when an out-of-network specialist is used at an in-network facility without your knowledge — and then receive an unexpectedly large bill. Common examples include out-of-network anesthesiologists or radiologists at an in-network hospital. The No Surprises Act, effective January 2022, protects patients from most surprise bills by limiting what providers can charge to in-network cost-sharing amounts in these situations. You generally cannot be balance billed in qualifying circumstances.

Sutures are stitches used to close a wound or surgical incision by bringing the edges of skin or tissue together so the area can heal properly. A doctor or nurse practitioner uses a needle and thread-like material — which may be absorbable or non-absorbable — to sew the wound closed after cleaning and numbing the area with a local anesthetic. Non-absorbable sutures need to be removed after several days to a few weeks, depending on the wound location and healing progress. Sutures reduce bleeding, lower infection risk, minimize scarring, and support the healing process.

The sweat test, also called the sweat chloride test, is the primary test used to diagnose cystic fibrosis (CF). It measures the amount of chloride (salt) in sweat. A gel or powder containing a medicine called pilocarpine is placed on the skin of the forearm and a mild electrical current is applied for about five minutes — a painless process called iontophoresis — to stimulate sweating. The sweat is then collected on special paper and analyzed. People with cystic fibrosis have much higher chloride levels in their sweat than average. The test is most commonly performed in children but can be done at any age. Results are usually available the same day.

A tablet is a solid dosage form made by compressing powdered medication into a firm disk shape that you swallow whole. Tablets may be plain, film-coated to make them easier to swallow, or enteric-coated to prevent dissolving until they reach the intestine and reduce stomach upset. Extended-release tablets deliver medication slowly over many hours and must never be crushed or chewed, as doing so releases the full dose at once and can cause serious harm. Immediate-release tablets dissolve quickly and act faster. Always ask your pharmacist before splitting or crushing a tablet, since not all formulations are safe to divide.

Telehealth refers to healthcare services delivered remotely via phone, video, or secure messaging platforms. Services include virtual doctor consultations, mental health therapy, chronic disease management, and prescription refills. Telehealth expanded dramatically during the COVID-19 pandemic. Coverage and cost-sharing vary by plan; many insurers now cover telehealth visits at parity with in-person visits. Telehealth is particularly useful for follow-up appointments, minor conditions, and patients in rural areas or with mobility limitations.

The telemedicine exception refers to DEA regulatory waivers allowing healthcare providers to prescribe certain controlled substances—including opioids, stimulants, and benzodiazepines—via telehealth without the in-person evaluation otherwise required by the Ryan Haight Act. Emergency waivers were first issued during the COVID-19 Public Health Emergency. The DEA has proposed making select exceptions permanent under a Special Registration framework. Whether your provider can prescribe a controlled substance through a video visit depends on which medications and conditions are covered under the current exception and applicable DEA rules in your state.

A telemetry unit is a hospital ward that continuously monitors patients' heart rhythms and vital signs using wireless sensors or leads attached to the body. It provides a level of care between a regular hospital room and an ICU. Telemetry patients typically have heart conditions, recent cardiac procedures, or other conditions requiring continuous rhythm monitoring. Staff at a central nursing station watch all patients' hearts on a screen simultaneously. If an abnormal rhythm occurs, an alarm alerts staff. You will wear a small monitoring device and leads on your chest. You can still walk around the unit wearing the monitor in many cases.

The temporal lobe is located on each side of your brain, roughly behind your temples. It processes sound and is essential for understanding spoken language. The left temporal lobe in most people handles speech comprehension, so damage there can make it hard to understand words even if you can hear them clearly. The temporal lobe also plays an important role in memory formation and storing long-term memories. It helps you recognize faces and familiar objects. Seizures that start in the temporal lobe can cause unusual sensations, deja vu, or brief episodes of staring. Temporal lobe epilepsy is one of the most common seizure disorders in adults.

Tenderness is pain or discomfort that occurs when pressure is applied to a specific area of the body, even if the area does not hurt without being touched. It is a key finding during physical examinations and can indicate inflammation, injury, infection, or bruising in that area. Tenderness in the abdomen can point to organ problems like appendicitis. Tenderness in muscles or joints may suggest strain, arthritis, or bursitis. A provider will often press on different areas to locate tender spots and determine their cause. Describing where and how much it hurts when pressed helps guide diagnosis and treatment decisions.

Tendinitis is inflammation or irritation of a tendon—the thick fibrous cords that attach muscle to bone. It most often results from repetitive motions or sudden injury and commonly affects the shoulder, elbow, wrist, knee, and heel. Pain is usually a dull ache near the affected joint, worsening with movement. Tenderness and mild swelling at the site are common. While most people recover with rest, ice, and anti-inflammatory medications, chronic tendinitis can progress to a tendon tear if untreated. Physical therapy, eccentric exercises, and occasionally corticosteroid injections are standard treatments.

ICD-10: M77

Tendons are the strong, flexible cords of tissue that connect your muscles to your bones. When a muscle contracts, it pulls on the tendon, which then pulls on the bone to create movement. Tendons are made of dense collagen fibers and are designed to handle high forces. Common tendons include the Achilles tendon at the back of your ankle and the patellar tendon below your kneecap. Tendons can become inflamed — a condition called tendinitis — or can tear or rupture completely, especially with sudden forceful movements or repeated stress over time. Tendon injuries can cause significant pain and reduced movement.

Tennis elbow, medically known as lateral epicondylitis, is an overuse injury causing pain and tenderness on the outside of the elbow where the forearm tendons attach to the bony bump. Despite its name, it is not limited to tennis players—any repetitive gripping or arm motion can cause it, such as painting, plumbing, or using a computer mouse. Symptoms include pain and burning on the outer elbow, weak grip strength, and worsening pain when gripping or lifting. Treatment includes rest, ice, physical therapy, bracing, and in some cases, corticosteroid injections or surgery.

ICD-10: M77

A tension headache is the most common type of headache. It feels like a steady, dull pressure or tightness around the forehead, sides, or back of the head—often described as a tight band squeezing the head. It is usually not severe enough to prevent normal activity and is not typically associated with nausea or vomiting. Triggers include stress, poor posture, eye strain, skipping meals, dehydration, and disrupted sleep. Most tension headaches respond well to over-the-counter pain relievers, rest, gentle neck stretches, and stress reduction. Frequent tension headaches (15 or more days per month) should be discussed with a provider for preventive treatment options.

ICD-10: G44

Tertiary insurance is a third health insurance plan that pays after both the primary and secondary insurers have processed a claim. This situation is uncommon but can occur for certain patients such as children covered under both parents' plans plus a government program like Medicaid or CHIP. The tertiary plan picks up remaining costs after the first two plans have paid their portions. Coordination of benefits rules apply in a specific order — Medicaid typically pays last when it is the tertiary payer. Having tertiary coverage can effectively eliminate most or all out-of-pocket costs, but billing and claims coordination can be complex and time-consuming for all parties involved.

A therapist is a licensed mental health professional who provides talk therapy, counseling, and other evidence-based treatments to help people manage mental health conditions, process difficult experiences, and improve their overall wellbeing. In the US, therapists may hold various credentials, including Licensed Clinical Social Worker (LCSW), Licensed Professional Counselor (LPC), Licensed Marriage and Family Therapist (LMFT), or Licensed Mental Health Counselor (LMHC). To be covered by insurance, your therapist must be licensed and in-network with your plan. Therapists do not prescribe medication — for medication, you need a psychiatrist or your primary care provider. Many therapists offer telehealth sessions, which can improve access, especially in rural areas.

Thoracentesis is a minimally invasive procedure in which a thin needle or tube is inserted through the chest wall into the space between the lungs and the chest wall (the pleural space) to remove excess fluid. This fluid buildup, called a pleural effusion, can result from infection, heart failure, cancer, or other conditions. The procedure is done under local anesthesia and takes about 15 to 30 minutes. Ultrasound guidance is commonly used to locate the fluid precisely and improve safety. Removing the fluid relieves symptoms such as shortness of breath. Fluid samples may be sent to a lab for analysis. Patients typically go home the same day. A chest X-ray is done afterward to ensure no complications such as collapsed lung occurred.

The thoracic duct is the largest vessel of the lymphatic system. It collects lymph — a clear fluid containing white blood cells, fats absorbed from the intestines, and waste products — from most of the body, including the lower limbs, abdomen, and left side of the chest. It runs from the abdomen up through the chest and empties into a large vein near the left shoulder, returning lymph to the bloodstream. The thoracic duct also carries fats absorbed from food in the small intestine. When the thoracic duct is damaged — by surgery, trauma, or cancer — a milky fluid called chyle can leak into the chest cavity, a condition called chylothorax that may require drainage.

The thoracic vertebrae are the twelve bones in the middle portion of your spine, labeled T1 through T12. They are located in the upper and mid-back region and are unique because each one connects to a pair of ribs, forming the rib cage that protects your heart and lungs. The thoracic spine is less flexible than the cervical and lumbar regions, which makes it more stable but also more prone to certain compression fractures in people with osteoporosis. Pain in the thoracic spine can result from poor posture, muscle strain, or fractures. Conditions like kyphosis (a forward rounding of the upper back) affect this region. Your doctor may order imaging to evaluate thoracic spine problems.

A throat culture is a laboratory test that identifies bacteria or other organisms causing a throat infection. A healthcare provider asks you to open your mouth wide and uses a sterile cotton swab to wipe cells from the back of your throat and tonsils. The swab is sent to a lab where organisms are grown on culture plates over 24–48 hours. If group A Streptococcus (strep throat) or other bacteria grow, lab staff identify the organism and may test antibiotic sensitivity. A throat culture is the confirmatory test for strep throat when a rapid strep test is negative but symptoms remain suspicious. The swab may cause a brief gagging sensation but is not painful.

Thrombocytopenia is a condition in which the blood has a lower-than-normal number of platelets, the cells that help blood clot. Low platelet counts increase the risk of abnormal bleeding. Causes include immune disorders (such as ITP), bone marrow problems, certain medications, infections, or as a side effect of chemotherapy. Mild thrombocytopenia may cause no symptoms, while severe cases can cause easy bruising, prolonged bleeding from cuts, nosebleeds, or blood in urine and stool. Treatment depends on the cause and may include corticosteroids, immunoglobulin therapy, platelet transfusions, or treating the underlying condition.

ICD-10: D69

Thyroid cancer is a malignant tumor of the thyroid gland, a butterfly-shaped gland in the neck that regulates metabolism and hormone production. It is one of the most common cancers in the US, and most types have excellent survival rates. The most common symptom is a painless lump in the neck. Risk factors include radiation exposure and family history. Most thyroid cancers grow slowly. Treatment usually involves surgical removal of part or all of the thyroid gland, often followed by radioactive iodine therapy and thyroid hormone replacement medication.

ICD-10: C73

The thyroid gland is a butterfly-shaped gland located in the front of your neck, just below the Adam's apple. It produces hormones — mainly thyroxine (T4) and triiodothyronine (T3) — that regulate your metabolism, meaning how fast your body burns energy. Thyroid hormones also affect heart rate, body temperature, growth, and mood. The pituitary gland in your brain controls the thyroid by releasing thyroid-stimulating hormone (TSH). An overactive thyroid (hyperthyroidism) causes weight loss, rapid heartbeat, and anxiety. An underactive thyroid (hypothyroidism) causes fatigue, weight gain, and cold intolerance. Thyroid nodules, goiters (enlarged thyroid), and thyroid cancer are all conditions that affect this gland.

A thyroid panel is a group of blood tests that measure how well your thyroid gland is working. The most common test is TSH (thyroid-stimulating hormone), which acts as a master signal. The panel may also include free T4 and free T3, which are the hormones your thyroid actually produces. An underactive thyroid (hypothyroidism) causes fatigue, weight gain, and feeling cold; an overactive thyroid (hyperthyroidism) causes rapid heartbeat, weight loss, and anxiety. Blood is drawn from a vein in your arm and no special preparation is usually needed. Results guide decisions about thyroid hormone replacement or medication to slow an overactive gland.

The tibia is your shinbone — the larger of the two bones in your lower leg. It runs from your knee down to your ankle. You can feel it as the hard ridge along the front of your lower leg. The tibia bears most of your body weight and is a key part of both the knee and ankle joints. It connects to the femur above and the fibula beside it. Tibia fractures are common sports and accident injuries. A break in the tibia may cause severe pain, swelling, and difficulty walking. Treatment can range from a cast to surgery with rods or plates.

Timely filing is the deadline set by a health insurance plan within which a claim must be submitted after the date of service. Common limits range from 90 days to one year for private insurers; Medicare generally allows one year from the date of service. Missing the timely filing deadline is a frequent reason claims are denied outright. As a patient, you are generally not responsible for claims your provider fails to file on time, but you should alert your insurer promptly if you receive a bill for a service that should have been submitted. Providers who accept Medicare assignment cannot bill you for claims denied solely because of late filing.

Tingling is an abnormal prickling, pins-and-needles, or buzzing sensation in the skin, often without complete numbness. It commonly affects the hands, feet, arms, and legs. Temporary tingling may result from crossing your legs, sleeping in an awkward position, or hyperventilating. Persistent tingling can indicate nerve damage from diabetes (peripheral neuropathy), vitamin B12 deficiency, carpal tunnel syndrome, thyroid problems, or multiple sclerosis. Sudden tingling on one side of the face, arm, or leg — especially paired with weakness or difficulty speaking — may signal stroke. Call 911 immediately in that case. Otherwise, report persistent tingling to your doctor for proper evaluation.

ICD-10: R20

Tinnitus is the perception of ringing, buzzing, hissing, clicking, or roaring sounds in one or both ears when no external sound is present. It can be intermittent or constant and range from mildly annoying to severely disabling. Common causes include noise-induced hearing damage, earwax blockage, ear infections, age-related hearing loss, certain medications (especially high-dose aspirin or NSAIDs), high blood pressure, and Meniere's disease. Tinnitus itself is usually not dangerous, but it should be evaluated if it is new, one-sided, pulsatile (beats with your heartbeat), or accompanied by hearing loss or dizziness. Most cases can be managed with treatment or sound therapy.

ICD-10: H93

Title VI of the Civil Rights Act of 1964 prohibits discrimination based on race, color, or national origin in programs and activities that receive federal financial assistance. In healthcare, this means hospitals, clinics, insurers, and other entities that accept Medicare, Medicaid, or federal grants cannot deny or provide inferior care because of a patient's race, ethnicity, or national origin. Title VI also requires these entities to provide meaningful access to patients with limited English proficiency—including free interpreter services and translated documents. Filing a complaint with the HHS Office for Civil Rights is the primary avenue for addressing language access failures or racial discrimination in federally funded healthcare.

Titration is the process of gradually adjusting your medication dose up or down to find the amount that is most effective for you with the fewest side effects. Your doctor may start you on a low dose and slowly increase it over weeks, particularly for medications used to treat seizures, depression, pain, blood pressure, or thyroid conditions. Titrating carefully reduces the risk of sudden side effects and allows your body to adjust. Follow your titration schedule closely and report any unusual symptoms to your provider promptly so adjustments can be made. Do not rush the process by skipping ahead to a higher dose on your own.

The tongue is a muscular organ in the mouth that plays essential roles in tasting, chewing, swallowing, and speaking. It is covered with thousands of tiny bumps called papillae, which contain taste buds that sense sweet, salty, sour, bitter, and savory (umami) flavors. The tongue moves food around while chewing and pushes it to the back of the throat during swallowing. It also shapes sounds into words by pressing against the teeth and roof of the mouth. The tongue is supplied by several nerves, including the facial nerve for taste and the hypoglossal nerve for movement. Conditions affecting the tongue include oral thrush (fungal infection), ulcers, and rarely, tongue cancer.

A tonsillectomy is surgery to remove the tonsils, two oval-shaped glands located at the back of the throat. It is most often performed to treat chronic or recurrent tonsil infections, obstructive sleep apnea caused by enlarged tonsils, or tonsils that harbor abscesses. The procedure is done under general anesthesia and takes about 30 to 45 minutes. Most patients go home the same day. Recovery typically takes 10 to 14 days, during which a sore throat is expected. A soft or liquid diet is recommended initially. Adequate hydration and rest are essential, and strenuous activity should be avoided to reduce the risk of bleeding. Pain is usually managed with oral medication.

The tonsils are two oval-shaped masses of lymphoid tissue located at the back of the throat, one on each side. They are part of the immune system and act as the body's first defense against bacteria and viruses that enter through the mouth and nose. In children, the tonsils are usually largest and most active. The tonsils can become infected (tonsillitis), causing a very sore throat, difficulty swallowing, fever, and swollen neck glands. Repeated infections or significantly enlarged tonsils that block breathing or swallowing may require surgical removal, a procedure called a tonsillectomy. The adenoids, located behind the nasal passages, are a related lymphoid tissue often removed at the same time.

A toothache is pain in or around a tooth that can range from mild tenderness to severe, constant aching or sharp throbbing. It may be triggered by eating, drinking hot or cold liquids, or biting down. Common causes include tooth decay (cavities), a cracked tooth, a dental abscess, gum disease, or an exposed tooth root. The pain sometimes spreads to the jaw, ear, or head. Mild discomfort may be managed temporarily with over-the-counter pain relievers and clove oil, but toothaches typically require dental treatment. Seek prompt care if the pain is severe, you have swelling in the jaw or face, fever, or difficulty opening your mouth or swallowing.

The trachea, commonly called the windpipe, is a tube about four to five inches long that runs from the back of your throat down into your chest. It is made of rings of cartilage — a firm but flexible tissue — that keep the tube open so air can pass through. When you breathe in, air travels down the trachea and then splits into two branches called the bronchi, one going to each lung. The trachea sits just in front of the esophagus, which is the food tube. Doctors may mention the trachea when discussing breathing problems, a breathing tube placed during surgery, or a procedure called a tracheostomy.

A tracheotomy is a surgical procedure in which an opening is made in the front of the neck into the windpipe (trachea) to create an airway. A tube is inserted through this opening to allow breathing when the upper airway is blocked or to assist patients who need long-term mechanical ventilation. It may be performed as an emergency or as a planned procedure in patients with serious respiratory problems. The procedure is done under local anesthesia with sedation or general anesthesia. A nurse or respiratory therapist will teach caregivers how to clean and care for the tracheostomy tube at home. Swallowing and speaking may be affected. A speech therapist may be involved in recovery.

Traction is a non-surgical treatment that applies a gentle pulling force to the spine or an injured limb to relieve pressure, reduce pain, and help restore proper alignment. Spinal traction — used for neck or back conditions such as herniated discs, nerve compression, or degenerative disc disease — may be performed manually by a physical therapist or using a mechanical device. Limb traction uses weights to hold a fractured bone in alignment while it heals. Sessions are typically short and are conducted by trained clinicians. Traction aims to widen the spaces between vertebrae or between bone segments to reduce compression and facilitate healing.

Transcranial Magnetic Stimulation (TMS) is a non-invasive brain stimulation therapy approved for treatment-resistant depression and certain other conditions. A device placed against the scalp delivers magnetic pulses that stimulate nerve cells in specific brain regions involved in mood regulation. Sessions last thirty to sixty minutes, and patients typically receive five sessions per week for four to six weeks. You remain awake throughout, and no anesthesia is needed. Common side effects are mild scalp discomfort or headache during sessions. TMS is an option for patients who have not improved with antidepressant medications.

A transdermal patch is a medicated adhesive patch placed on the skin that releases a controlled amount of medication into your bloodstream through the skin over hours or days. Common medications delivered by patch include opioid pain relievers, nicotine for smoking cessation, hormones, nitroglycerin for heart conditions, and motion sickness drugs. Patches provide steady medication levels without the peaks and valleys of oral pills. Apply your patch to clean, dry, hairless skin and rotate the application site with each replacement. Dispose of used patches safely by folding the adhesive sides together, since they still contain active drug that can seriously harm children, pets, or others who contact them.

A trauma center is a hospital equipped and staffed to treat severe physical injuries such as those caused by car accidents, falls, gunshot wounds, or industrial accidents. In the United States, trauma centers are classified by levels (Level I through Level IV), with Level I being the most comprehensive and capable of treating the most critical injuries. Ambulances and helicopters transport patients to the nearest appropriate level. If you or a loved one is taken to a trauma center, it means the injury is serious. A trauma team is immediately assembled to evaluate and stabilize the patient upon arrival.

A trauma team is a group of highly trained healthcare professionals assembled immediately when a seriously injured patient arrives at a trauma center or emergency department. The team typically includes a trauma surgeon, emergency physician, nurses, anesthesiologist, respiratory therapist, and other specialists as needed. They work simultaneously and rapidly to assess injuries, stabilize the patient, and determine if surgery is needed. The room and equipment are prepared before the patient arrives when pre-notification is given by paramedics. Seeing a large team in the room may feel overwhelming, but each member has a specific role. Family members are kept updated by a designated staff member.

Traumatic brain injury (TBI) results from a sudden blow, jolt, or penetrating injury to the head that disrupts normal brain function. Severity ranges from mild concussions to severe injuries causing prolonged unconsciousness. Symptoms can include headache, confusion, memory loss, mood changes, seizures, and sensory problems. TBI can have lasting effects on thinking, behavior, communication, and physical function. Falls and motor vehicle accidents are leading causes. Treatment depends on severity and may include emergency care, surgery, rehabilitation therapies, and long-term support for cognitive and emotional recovery.

ICD-10: S09

A tremor is an involuntary, rhythmic shaking of a body part, most often the hands. Rest tremors occur when the limb is relaxed; action tremors occur during movement. Essential tremor is the most common type and often hereditary. Parkinson's disease classically causes a resting pill-rolling tremor of the fingers. Other causes include hyperthyroidism, medication side effects, excessive caffeine, alcohol withdrawal, anxiety, and low blood sugar. Most tremors are not life-threatening, but a doctor can identify the cause and offer treatment. Tremors that appear suddenly, worsen rapidly, or accompany slurred speech, weakness, or loss of coordination need urgent evaluation.

ICD-10: R25

Triage is the process of quickly assessing patients when they arrive at the emergency room to determine the urgency of their medical needs. A trained triage nurse asks about your symptoms, checks vital signs, and assigns a priority level. Patients with life-threatening emergencies—such as chest pain, stroke, or severe bleeding—are seen immediately. Those with less critical conditions wait longer. You may feel frustrated waiting, but triage ensures the sickest patients receive care first. The triage nurse does not make a diagnosis but decides how quickly you need to be seen by a physician.

Clinical trials are conducted in four sequential phases. Phase I trials test a new treatment in a small group (20–100 people) to evaluate safety, dosage range, and side effects. Phase II trials expand to more participants (100–300) to assess effectiveness and continue safety evaluation. Phase III trials involve large numbers (1,000–3,000+) comparing the new treatment against standard care—successful results are typically required for FDA approval. Phase IV trials occur after approval to monitor long-term effects and rare side effects in the general population. Knowing the trial phase helps you understand what is already established about the treatment's safety and effectiveness.

The trigeminal nerve is the fifth cranial nerve and the largest of the twelve cranial nerves. It carries sensation from the face, scalp, teeth, gums, sinuses, and parts of the mouth to the brain, allowing you to feel touch, pain, and temperature in these areas. It also controls the muscles you use for chewing. The nerve has three main branches: the ophthalmic branch (forehead and eyes), the maxillary branch (cheeks, upper lip, and upper teeth), and the mandibular branch (lower jaw, lower teeth, and chin). Trigeminal neuralgia is a condition that causes sudden, severe, electric shock-like facial pain triggered by everyday activities such as eating, talking, or touching the face. It is one of the most painful conditions known in medicine.

A trimester is one of the three roughly equal stages of pregnancy, each lasting about 12 to 14 weeks. The first trimester runs from week 1 to week 13, when major organs form and miscarriage risk is highest. The second trimester (weeks 14–27) is often the most comfortable period; you may feel the baby move. The third trimester (weeks 28–40+) focuses on growth and preparation for birth. Your provider will schedule different tests and screenings depending on which trimester you are in, so knowing your trimester helps you understand what to expect at each visit.

ICD-10: Z34

Tuberculosis is a bacterial infection caused by Mycobacterium tuberculosis that primarily affects the lungs. It spreads through the air when an infected person coughs, sneezes, or speaks. Active TB causes symptoms such as a persistent cough lasting more than three weeks, coughing up blood, night sweats, weight loss, and fever. Latent TB infection has no symptoms and is not contagious, but it can become active. Treatment requires a combination of antibiotics taken for at least six months. Completing the full course is critical to prevent drug-resistant TB. Testing and early treatment protect individuals and the community.

ICD-10: A15

The two-midnight rule is a Medicare billing policy stating that when a hospital physician expects a patient to need care spanning at least two midnights, the stay is presumed an appropriate inpatient admission billable under Part A. Stays expected to be shorter are generally classified as outpatient observation status, billed under Part B—which may result in higher patient cost-sharing and disqualifies the stay from counting toward the three-day inpatient requirement needed for subsequent skilled nursing facility coverage. Always ask your care team whether you are admitted as inpatient or are under observation status, since the financial implications are significant.

Type 1 diabetes is an autoimmune disease in which the body's immune system attacks and destroys the insulin-producing cells in the pancreas. Without insulin, blood sugar rises to dangerous levels. It is usually diagnosed in children and young adults, though it can appear at any age. Symptoms include extreme thirst, frequent urination, unintended weight loss, and fatigue. People with type 1 diabetes must take insulin every day to survive. There is no cure, but with proper management including insulin therapy, blood sugar monitoring, and careful diet, people can live full and healthy lives.

ICD-10: E10

Type 2 diabetes is a chronic condition in which the body does not use insulin properly, causing blood sugar levels to rise too high. Insulin is a hormone that helps move sugar from your blood into your cells for energy. Over time, high blood sugar damages nerves, kidneys, eyes, and blood vessels. Common symptoms include increased thirst, frequent urination, fatigue, and blurred vision. Risk factors include excess weight, physical inactivity, and family history. Treatment includes healthy eating, regular exercise, blood sugar monitoring, and medications or insulin therapy.

ICD-10: E11

Ulcerative colitis is a chronic inflammatory bowel disease that causes long-lasting inflammation and ulcers in the innermost lining of the large intestine and rectum. It is characterized by periods of flare-ups and remission. Symptoms include diarrhea often with blood or pus, abdominal cramps and pain, rectal pain and bleeding, urgency to defecate, fatigue, and weight loss. The exact cause is unclear but involves an abnormal immune response. Treatment includes anti-inflammatory medications, immunosuppressants, and biologics to control inflammation. In severe or treatment-resistant cases, surgery to remove the colon can be curative. Long-term monitoring is recommended to screen for colon cancer.

ICD-10: K51

The ulna is one of the two bones in your forearm, running along the pinky-finger side from your elbow to your wrist. It is the longer of the two forearm bones and forms the main part of the elbow joint, creating the bony bump you feel at the tip of your elbow. The ulna works closely with the radius to allow the forearm to rotate. Fractures of the ulna can result from direct impacts, falls, or trying to block a blow, sometimes called a nightstick fracture. Injuries near the elbow, such as an olecranon fracture, affect the bony tip and may need surgical repair.

An ultrasound uses high-frequency sound waves to create real-time images of organs, blood vessels, and tissues inside your body. A technician applies a clear gel to your skin and moves a small handheld device called a transducer over the area being examined. The device sends sound waves into your body and records the echoes that bounce back. The test is painless and does not use radiation. It usually takes 20 to 45 minutes. Depending on the area being imaged, you may need a full bladder or may need to fast beforehand. Ultrasound is commonly used to examine the abdomen, pelvis, thyroid, blood vessels, and developing fetuses during pregnancy.

The umbilical cord is the lifeline connecting your baby to the placenta during pregnancy, carrying oxygen and nutrients to the baby and removing waste. At birth, the cord is clamped and cut — often the partner is offered the chance to cut it. A small stump remains on the baby's navel and naturally dries up and falls off within 1 to 3 weeks. Keep the stump clean and dry; fold diapers below it until it falls off. Call your baby's doctor if you see redness spreading around the navel, foul smell, or oozing — these may signal infection (omphalitis). Delayed cord clamping (waiting 30–60 seconds before cutting) is now recommended by the AAP.

ICD-10: P96

An undue hardship waiver is an exemption from a financial or legal obligation granted when complying would impose an unreasonable burden. In healthcare, this most commonly applies to Medicaid estate recovery—allowing a family to keep a home or asset that would otherwise be subject to repayment after a Medicaid beneficiary's death—when recovery would cause the surviving family undue hardship. Each state defines undue hardship differently, but criteria typically consider whether the asset is the family's sole income-producing property or the only home for a dependent relative. Applications are submitted to the state Medicaid agency.

Unexplained weight loss is a decrease of 5% or more of body weight over six to twelve months without intentional dieting or increased exercise. It can be a sign of serious illness, including cancer, diabetes, thyroid disease, inflammatory bowel disease, chronic infection such as tuberculosis or HIV, depression, or heart failure. The cause is not always serious, but significant unintended weight loss always warrants medical evaluation. Your doctor will likely order blood tests and imaging to identify the underlying reason. Early diagnosis improves treatment outcomes in many conditions.

ICD-10: R64

An uninsured person is someone who has no health insurance coverage—not through an employer, government program such as Medicaid or Medicare, or an individual marketplace plan. The uninsured often face significant barriers to care, including full-price chargemaster billing and avoidance of needed care due to anticipated cost. Federal law still requires hospital emergency departments to screen and stabilize all patients regardless of insurance status. If you are uninsured, you may qualify for Medicaid, ACA marketplace coverage with premium tax credits, or federally qualified health centers that charge on a sliding-fee scale based on income.

Upcoding is fraudulent or abusive billing practice in which a healthcare provider submits a billing code for a more complex, higher-cost service than was actually performed. For example, billing an extended office visit code for what was a brief routine check-up. Upcoding increases the provider's reimbursement and may also increase your cost-sharing if you pay a percentage of the charge. It is illegal under federal fraud and abuse laws and can result in large fines or exclusion from Medicare and Medicaid. Patients can spot upcoding by carefully reviewing their EOB and asking for an itemized bill if the charges seem unusually high.

The ureters are two thin muscular tubes, one connected to each kidney, that carry urine from the kidneys down to the bladder. Each ureter is roughly 10 to 12 inches long. Urine moves through the ureter by waves of muscle contractions rather than by gravity alone. The most common problem affecting ureters is a kidney stone getting stuck inside one, which causes sudden, severe pain that can radiate to the groin. This is called ureterolithiasis or ureteral obstruction. Infections can also affect the ureters. In some cases, the ureter may be blocked and need a small tube called a stent to keep it open.

The urethra is the tube that carries urine from the bladder to the outside of the body. In women, it is short (about 1.5 inches) and opens just above the vaginal opening. In men, it is much longer (about 8 inches) and passes through the prostate and the length of the penis, also serving as the passage for semen. Because the female urethra is shorter, women are more prone to urinary tract infections. Common problems include infections, narrowing of the tube (stricture), and inflammation. Burning or pain when urinating is often a sign of urethral or bladder infection. Your doctor may do a urine test or scope to check.

An urgent care center is a walk-in medical facility for conditions that need prompt attention but are not life-threatening emergencies. Common reasons to visit include minor fractures, sprains, infections, fever, and minor wounds. Urgent care centers are open beyond regular office hours, often evenings and weekends, and typically cost significantly less than emergency rooms. Most accept insurance; copays usually range from $25–$75 in-network. They are not appropriate for chest pain, stroke symptoms, or severe injuries.

Urgent prior authorization—also called expedited prior authorization—is an accelerated insurance review for requests where waiting for a standard review could seriously jeopardize the patient's health or safety. Under federal rules for urgent care situations, insurers must respond to expedited requests within 72 hours. For life-threatening emergencies, care must be provided first and prior authorization is not required in the emergency department. Your doctor must indicate on the request why the situation is urgent. If an urgent authorization is denied, you have the right to an expedited appeal, which must also receive a faster response.

A urinalysis (UA) is a physical, chemical, and microscopic examination of your urine. It checks color, clarity, pH, protein, glucose, ketones, bilirubin, red blood cells, white blood cells, and bacteria. You provide a clean-catch midstream urine sample by urinating a little into the toilet, then catching the middle stream in a sterile cup provided by the clinic. A urinalysis can reveal urinary tract infections, kidney disease, diabetes, liver problems, and dehydration. Results are often available within hours. Doctors order urinalysis during routine physical exams, pregnancy checks, pre-surgical evaluations, and whenever you report symptoms like painful or frequent urination.

A urinary catheter is a thin, flexible tube inserted through the urethra into the bladder to drain urine. In hospitals, it is most commonly a Foley catheter, which stays in place held by a small balloon inside the bladder. Catheters are used when patients cannot urinate on their own due to surgery, illness, paralysis, or certain procedures. They are also used to accurately measure urine output in critically ill patients. Catheters carry a risk of urinary tract infection (UTI), so hospitals try to remove them as soon as safely possible. Tell your nurse if you experience burning, leakage, or pain around the catheter site.

Urinary incontinence is the unintentional leaking of urine. It affects millions of Americans and is more common in women and older adults, though it can occur at any age. The two most common types are stress incontinence, where leakage occurs with physical exertion like coughing, sneezing, or laughing, and urge incontinence, where leakage follows a sudden uncontrollable urge to urinate. Causes include weakened pelvic floor muscles, nerve damage, enlarged prostate, urinary tract infections, and certain medications. While often underreported due to embarrassment, urinary incontinence is treatable and should be discussed openly with a healthcare provider.

ICD-10: R32

A urinary tract infection is an infection in any part of the urinary system, including the kidneys, bladder, ureters, or urethra. Most UTIs involve the bladder and urethra. They are caused by bacteria, most commonly Escherichia coli, and are significantly more common in women than men. Symptoms include a burning sensation when urinating, frequent or urgent need to urinate, cloudy or strong-smelling urine, and pelvic pain. Most uncomplicated UTIs are treated with a short course of antibiotics. Drinking plenty of water and urinating after sexual activity can help prevent recurrences. Kidney infections require more aggressive treatment.

ICD-10: N39

Urinary urgency is the sudden, strong, and difficult-to-ignore need to urinate. Unlike the gradual sensation of a full bladder, urgency feels like an immediate need that may be hard to defer. It is a hallmark symptom of overactive bladder and can lead to urge urinary incontinence when the urge cannot be controlled. It can also result from urinary tract infections, interstitial cystitis, bladder stones, prostate conditions in men, and neurological diseases. Urgency that is new, worsening, or accompanied by burning, blood in the urine, or pelvic pain should be reported to a healthcare provider.

ICD-10: R39

A urine culture is a laboratory test that grows any bacteria or yeast present in your urine on a special dish, then identifies exactly which organism is causing an infection. You collect a clean-catch midstream urine sample in a sterile cup. The lab incubates the sample for 24–48 hours. If bacteria grow, the lab also performs sensitivity testing to find out which antibiotics will kill the specific organism, helping your doctor prescribe the right treatment. This test is more precise than a urinalysis alone. Doctors order a urine culture when they suspect a urinary tract infection (UTI), kidney infection, or when a UTI keeps coming back despite treatment.

Uterine cancer, most commonly endometrial cancer, is a malignant tumor that begins in the lining of the uterus (the endometrium). It is the most common gynecologic cancer in the United States. The most common symptom is abnormal uterine bleeding, especially after menopause. Risk factors include obesity, diabetes, hormone imbalances, and family history. Because it often causes early warning symptoms, many cases are caught at an early and treatable stage. Treatment typically involves hysterectomy (surgical removal of the uterus), sometimes combined with radiation or chemotherapy.

ICD-10: C54

Uterine fibroids are noncancerous growths of the uterus that often appear during childbearing years. They are the most common benign tumors in women of reproductive age. Many women with fibroids have no symptoms, but some experience heavy or prolonged menstrual bleeding, pelvic pressure or pain, frequent urination, and difficulty becoming pregnant. The exact cause is unknown, but hormones and genetics play a role. Fibroids often shrink after menopause. Treatment options range from medication to manage symptoms to minimally invasive procedures or hysterectomy, depending on size, symptoms, and reproductive goals.

ICD-10: D25

The uterus, commonly called the womb, is a hollow, pear-shaped organ in a woman's lower abdomen between the bladder and the rectum. It is where a fertilized egg implants and a baby grows during pregnancy. Each month, the lining of the uterus (called the endometrium) thickens to prepare for a possible pregnancy. If pregnancy does not occur, that lining is shed during menstruation. Common conditions involving the uterus include fibroids (benign growths), endometriosis, uterine cancer, and infections. Symptoms like abnormal bleeding, pelvic pain, or painful periods should be discussed with your doctor. The uterus is typically examined with an ultrasound.

Utilization review (UR) is the process insurers use to evaluate whether the medical care you receive — or plan to receive — is medically necessary, appropriate, and efficient. It includes three phases: prospective review (before care, which is prior authorization), concurrent review (during an inpatient stay to check ongoing necessity), and retrospective review (after care to verify appropriateness). UR is performed by nurses or physicians using established clinical criteria. If your care does not meet the criteria, the insurer may deny or reduce coverage. Federal law gives you the right to appeal utilization review decisions, and many states require independent external review.

Vaccination refers specifically to the act of receiving a vaccine — a biological preparation that induces immunity to a particular infectious disease. Vaccines may be given as an injection, nasal spray, or oral dose. They contain weakened or inactivated pathogens, specific proteins, or mRNA instructions that teach the immune system to respond to a real infection. Routine vaccination in the US follows schedules set by the CDC for children and adults. Annual flu vaccination is widely recommended. Vaccines have largely eliminated or drastically reduced diseases like smallpox, polio, and measles. Most vaccines are covered under preventive care at no cost-sharing under the Affordable Care Act.

Vaginal delivery is the birth of a baby through the vagina, the most common way babies are born. It occurs in two main stages: active labor, when the cervix dilates to 10 centimeters; and pushing, when the baby moves through the birth canal. A vaginal birth may be spontaneous (labor begins naturally) or assisted with induction. Sometimes forceps or a vacuum device are used to help guide the baby out. Recovery from vaginal delivery is generally faster than cesarean (C-section) recovery. Pain management options include epidural anesthesia, IV medications, and non-medicated techniques.

ICD-10: O80

The vagus nerve is the tenth cranial nerve and the longest nerve in the body — it travels from the brainstem all the way down to organs in the chest and abdomen, including the heart, lungs, and digestive tract. Its name means wandering in Latin, reflecting how far it travels. The vagus nerve is a key part of the parasympathetic nervous system, which controls the body's rest and digest responses. It slows the heart rate, stimulates digestion, and helps regulate inflammation. In the head and neck, it helps control swallowing, speech, and gag reflex. Vagus nerve stimulation (VNS) is a medical therapy using small electrical pulses to treat epilepsy and depression. Vasovagal syncope (fainting from sudden stimulation of the nerve) is also a well-known condition.

Value-based care is a healthcare payment and delivery model that rewards providers for achieving better patient health outcomes rather than simply for the volume of services they deliver. Under value-based contracts, providers receive bonuses for hitting quality and efficiency targets — such as reducing hospital readmissions or controlling chronic disease — and may face penalties for poor outcomes. For patients, value-based care is intended to mean better coordinated, more patient-centered treatment. Common value-based arrangements include Accountable Care Organizations (ACOs), Patient-Centered Medical Homes (PCMHs), and bundled payment programs. Medicare and private insurers increasingly use these models.

Valvular heart disease occurs when one or more of the four heart valves does not work properly. The valves control blood flow through and out of the heart. A valve may fail to open fully (stenosis), restricting blood flow, or fail to close completely (regurgitation), allowing blood to leak backward. Common affected valves are the aortic and mitral valves. Symptoms include shortness of breath, fatigue, palpitations, chest pain, and leg swelling. Causes include aging, prior infections such as rheumatic fever, birth defects, and other heart conditions. Treatment may include medications to manage symptoms or surgery or catheter-based procedures to repair or replace the affected valve.

ICD-10: I08

Venous insufficiency is a condition where the veins in the legs have difficulty sending blood back up to the heart. Healthy veins have one-way valves that prevent blood from flowing backward. When these valves weaken or become damaged, blood pools in the legs. Symptoms include leg swelling, aching, heaviness, and cramping, as well as varicose veins, skin discoloration, and in advanced cases, slow-healing ulcers near the ankles. Risk factors include prolonged standing or sitting, obesity, prior blood clots, pregnancy, and family history. Treatment includes compression stockings, leg elevation, regular walking, and in some cases procedures to close or remove damaged veins.

ICD-10: I87

The ventricles are the two lower chambers of the heart — the heart's main pumping chambers. The right ventricle pumps oxygen-poor blood out to the lungs to pick up oxygen. The left ventricle, the largest and most muscular of the four chambers, pumps oxygen-rich blood out to the entire body through the aorta. Heart failure often involves the ventricles not pumping strongly enough or not relaxing properly to fill well. An ejection fraction — a number your doctor may mention — measures how much blood the left ventricle pumps out with each beat. A normal ejection fraction is 55 percent or higher.

Vertigo is a specific type of dizziness where you feel as if you or the room is spinning or tilting, even while still. The most common cause is benign paroxysmal positional vertigo (BPPV), where tiny crystals in the inner ear shift. Other causes include Meniere's disease, labyrinthitis, and less commonly stroke or brain tumors. Episodes can last seconds to hours. Call 911 if vertigo appears suddenly with double vision, slurred speech, weakness, difficulty walking, or severe headache, as these can be signs of stroke or other serious brain conditions requiring immediate treatment.

ICD-10: H81

Vision changes refer to any new or unexpected alteration in what or how you see. These can include blurriness, dimming, blind spots, color distortion, sensitivity to light, or sudden loss of vision in one eye. Gradual changes are often caused by refractive errors, cataracts, glaucoma, or macular degeneration. Sudden vision changes — especially in one eye or paired with headache, eye pain, or flashing lights — can signal a detached retina, stroke, or acute glaucoma. Call 911 or go to an emergency room immediately if vision changes are sudden, severe, or affect one eye without warning. Early treatment can prevent permanent vision loss.

ICD-10: H53

Vital signs are basic measurements that indicate how well the body is functioning. The standard vital signs measured in hospitals include blood pressure, heart rate (pulse), respiratory rate (breathing rate), body temperature, and oxygen saturation (how much oxygen is in the blood). Healthcare providers check vital signs frequently in the hospital, especially in the emergency room and ICU. Abnormal vital signs can signal a medical emergency and prompt immediate action. Ask your nurse what your readings mean if they seem to be concerning or if you notice staff responding urgently to your monitor.

The vitamin D blood test measures 25-hydroxyvitamin D, the form your liver makes after you absorb vitamin D from sunlight or food. This is the most reliable way to assess your vitamin D status. Low vitamin D is linked to weak bones (osteoporosis, rickets), muscle weakness, and immune problems. Very high levels from excessive supplementation can cause toxicity. Blood is drawn from a vein in your arm. No fasting is required. Results above 30 ng/mL are generally considered sufficient; below 20 ng/mL is deficient. Doctors order this test for patients at risk of bone disease, people with limited sun exposure, those who are obese, or individuals with gut absorption disorders.

The vocal cords, also called vocal folds, are two bands of smooth muscle tissue located inside the larynx (voice box). They open to allow breathing and close when you speak. When air from your lungs passes through the closed vocal cords, they vibrate rapidly to produce sound. The pitch of your voice depends on how tightly the muscles stretch the cords — tighter means a higher pitch. Men generally have longer, thicker vocal cords, which produces a lower voice. Common problems include laryngitis (swelling from infection or overuse), nodules (callus-like growths from vocal strain), polyps, and paralysis of one or both cords. Throat cancer can also affect the vocal cords, so persistent hoarseness should be evaluated.

Vomiting is the forceful expulsion of the stomach's contents through the mouth. It is often accompanied by nausea and may be triggered by infections, food poisoning, motion sickness, medications, pregnancy, or underlying gastrointestinal conditions. Repeated vomiting can quickly lead to dehydration, especially in children and older adults. Seek immediate medical care if vomiting contains blood or looks like coffee grounds, if it is accompanied by severe abdominal pain or chest pain, follows a head injury, or if the person cannot keep any fluids down for more than 24 hours. Dehydration symptoms include dry mouth, dizziness, and little or no urine output.

ICD-10: R11

A waiting period is the time between when you enroll in a health insurance plan and when your coverage becomes active, or the time before a specific benefit begins. Under the ACA, employer health plans cannot impose waiting periods longer than 90 days for new employees. A waiting period differs from a pre-existing condition exclusion, which the ACA prohibits outright. Medicare has a 24-month waiting period for Social Security Disability Insurance recipients before Medicare coverage starts. Some plans also impose separate waiting periods for dental or vision benefits. Understanding your plan's waiting periods helps you plan for potential coverage gaps.

Weight gain refers to an increase in body weight over time. It may result from eating more calories than the body burns, but it can also be caused by medical conditions such as hypothyroidism, polycystic ovary syndrome, Cushing syndrome, or fluid retention from heart, kidney, or liver disease. Certain medications, including steroids, antidepressants, and antipsychotics, can also cause weight gain. Rapid or unexplained weight gain should be evaluated by a healthcare provider. Treatment depends on the underlying cause and may involve dietary changes, exercise, medication adjustment, or management of an underlying condition.

A well-child visit is a routine checkup with your child's pediatrician to monitor growth and development, administer vaccines, and screen for problems before symptoms appear. The AAP recommends visits at 3–5 days after birth, 1 month, 2 months, 4 months, 6 months, 9 months, 12 months, 15 months, 18 months, 2 years, 2.5 years, and then annually through age 21. At each visit the doctor measures height, weight, and head circumference; checks developmental milestones; reviews the immunization schedule; and answers your parenting questions. Well-child visits are fully covered by most insurance plans as preventive care.

ICD-10: Z00

Wheezing is a high-pitched whistling or squeaking sound made when you breathe, usually heard most clearly when breathing out. It happens when the airways in your lungs are narrowed, swollen, or blocked. Asthma and COPD are the most common causes, but wheezing can also result from allergies, respiratory infections, heart failure, or a foreign object in the airway. New or severe wheezing, especially with difficulty breathing or blue-tinged lips or fingernails, is a medical emergency. Mild or known asthma-related wheezing should still be evaluated if your rescue inhaler is not helping.

ICD-10: R06

White blood cells are the cells of the immune system that protect your body against infection and disease. They are produced in the bone marrow and circulate through the blood and lymph nodes. There are several types, including neutrophils (which fight bacteria), lymphocytes (which produce antibodies and attack viruses), and monocytes. A complete blood count (CBC) blood test measures your white blood cell count. A high count can indicate infection, inflammation, or certain cancers like leukemia. A low count (called leukopenia) can occur after chemotherapy or with certain immune disorders, making you more vulnerable to infections. The white blood cell count is a key measure of immune health.

Wound care involves cleaning, treating, and dressing injuries, surgical incisions, pressure sores, diabetic ulcers, or other skin wounds to promote healing and prevent infection. It may be done in a clinic, hospital, or at home. Care includes removing dead tissue (debridement), applying specialized dressings, and monitoring for signs of infection such as redness, swelling, or drainage. Some complex wounds require advanced treatments like negative pressure wound therapy or bioengineered skin substitutes. Regular follow-up appointments ensure proper healing and allow adjustments to the treatment plan as the wound improves.

An X-ray is a quick imaging test that uses a small dose of radiation to take pictures of structures inside your body, especially bones and lungs. You will stand, sit, or lie still while a machine sends radiation through your body onto a detector plate. The test takes only a few minutes and is painless. Dense structures like bone appear white; soft tissue appears gray; air-filled areas like lungs appear dark. Your doctor may use X-rays to look for broken bones, pneumonia, or other abnormalities. You may be asked to wear a lead apron to protect other body parts from radiation exposure.