Medical terms A–Z

A repeat dose that reminds the immune system of a threat it already knows, restoring protection that has quietly faded.

Emotions run hotter and settle more slowly, and because the triggers are usually other people, relationships carry most of the strain.

A type of radiation therapy.

Plant origin says nothing about strength or safety, since many potent drugs began as plant extracts and some plants are outright poisonous.

A toxin made by the bacterium Clostridium botulinum.

Nearly all nutrition is taken up in the first section, while the second exists largely to reclaim water before waste is passed.

The way the intestines work in terms of how often there are bowel movements, the ability to control when to have a bowel movement, and whether the stools are hard and dry as in constipation or…

A bowel movement is the elimination of solid waste from the digestive tract, and its frequency, consistency, and color vary widely among healthy people.

Bowen disease is an early, noninvasive skin cancer confined to the epidermis, most often linked to sun exposure rather than a single cause.

A substance used in a type of radiation therapy called boron neutron capture therapy.

A benign (not cancer) condition in which an overgrowth of prostate tissue pushes against the urethra and the bladder, blocking the flow of urine.

A substance being studied in the treatment of cancer.

The pattern of what is weak and what is numb points to where along the nerve network the trouble actually sits.

Everything the arm can do or feel passes through one braided tangle behind the collarbone, which is why damage there spreads so widely.

Brachytherapy delivers radiation from a sealed source placed directly inside or next to a tumor, concentrating the dose while sparing nearby tissue.

A slow pulse is a problem only when it fails to deliver enough blood; in a trained athlete the same reading is fitness.

A gene that makes a protein called B-RAF, which is involved in sending signals in cells and in cell growth.

Cancer in the brain has far more often arrived from elsewhere than started there, and that origin decides how it is treated.

The brain stem connects the brain to the spinal cord and controls fundamental automatic functions including breathing, heart rate, and consciousness.

A tumor located in the part of the brain that connects to the spinal cord (the brain stem).

A tumor in the part of the brain that connects to the spinal cord (the brain stem).

Inside a closed skull, even a growth that never spreads anywhere can do harm simply by taking up room.

A gene on chromosome 17 that normally helps to suppress cell growth.

A gene on chromosome 13 that normally helps to suppress cell growth.

A computer program that uses statistics to predict whether a person has an inherited mutation (change) in the BRCA1 and BRCA2 genes.

Intense increases in pain that occur with rapid onset even when pain-control medication is being used.

A gland that reorganizes itself repeatedly across a lifetime, which is why what counts as normal in it keeps changing.

Receptor testing turned one disease into several, since what a tumor responds to now shapes treatment more than its size does.

There are 2 types of breast carcinoma in situ: ductal carcinoma in situ (DCIS) and lobular carcinoma in situ (LCIS).

A description of what a mammogram shows rather than of how a breast feels, and it cannot be judged by touch.

A thin tube in the breast that carries milk from the breast lobules to the nipple.

A method used to examine the lining of the breast ducts to look for abnormal tissue.

A silicone gel-filled or saline-filled sac placed under the chest muscle to restore breast shape.

A section of the breast that contains the lobules (the glands that make milk).

A small part of a lobe in the breast.

Surgery to rebuild the shape of the breast after a mastectomy.

An exam by a woman of her breasts to check for lumps or other changes.

An operation to remove the breast cancer but not the breast itself.

An operation to remove the breast cancer but not the breast itself.

The long flat bone that forms the center front of the chest wall.

A questionnaire used to measure pain.

A substance being studied in the treatment of cancer.

A substance that is being studied in the treatment of infections caused by herpesvirus, including herpes-zoster (shingles).

Treatment to boost or restore the ability of the immune system to fight cancer, infections, and other diseases.

The bronchi are the two large air passages branching from the trachea, one into each lung, that form the lungs' main airway entrance.

Bronchial describes anything relating to the bronchi, the large airways connecting the windpipe to the lungs, as in bronchial asthma or bronchial breath sounds.

Cancer that forms in tissues of the bronchi (large air passages in the lungs including those that lead to the lungs from the windpipe).

A procedure in which cells are taken from the inside of the airways that lead to the lungs.

A procedure in which cells are taken from the inside of the airways that lead to the lungs.

A procedure in which cells are taken from the inside of the airways that lead to the lungs.

A bronchiole is one of the smallest airway branches in the lungs, carrying air from the larger bronchi toward the air sacs where gas exchange occurs.

Bronchiolitis obliterans is a rare, irreversible lung condition in which scarring narrows or blocks the smallest airways, sometimes following transplant or toxic exposure.

One word covers a self limiting cough after a virus and a lasting change in the airways caused by years of irritation.

A medicine that relaxes the muscle squeezing the airways, so a narrowed breathing tube opens up again.

An older umbrella name for lung cancer arising in the airway lining, still met in pathology reports and textbooks.

A bronchoscope is a thin, lighted instrument passed into the airway to directly view and sample tissue from the trachea and bronchi.

A procedure that uses a bronchoscope to examine the inside of the trachea, bronchi (air passages that lead to the lungs), and lungs.

The reversible half of an asthma attack: muscle squeezing airways shut, distinct from the swelling and mucus that clear far more slowly.

A bronchus is one of the two large airways connecting the trachea to a lung, continuing the path air follows into the smaller airways.

A substance being studied in the treatment of cancer.

A drug that makes cancer cells more sensitive to radiation and is also used as a diagnostic agent to determine how fast cancer cells grow.

Blood that escaped a broken vessel and has nowhere to go, changing color over days as the body dismantles it.

A delivery vehicle rather than a drug: its entire job is to sit inside the tumor and wait for a neutron beam.

A substance being studied in the treatment of breast cancers caused by mutations (changes) in the BRCA1 and BRCA2 genes.

The inner lining of the cheeks.

Its usefulness rests less on potency than on delivery, since the liver destroys most of a swallowed dose before it reaches the wider body.

An eastern North American perennial herb.

An eastern North American perennial herb.

A substance, such as fiber in food, that adds bulk and water to stools so that they can pass more easily through the intestines (lower part of the digestive tract).

BUN is a blood test that measures urea nitrogen, a waste product cleared by the kidneys, to help assess kidney function.

Bupivacaine is a long acting local anesthetic widely used for regional nerve blocks, epidurals, and pain control after surgery.

Chosen as often for what it does not do, since weight gain and sexual side effects are less common than with serotonin antidepressants.

A roadside weed eaten as a vegetable in East Asia, sold as a blood cleanser, and the plant that inspired hook-and-loop fastening.

A rare, fast-growing type of leukemia (blood cancer) in which too many white blood cells called B lymphocytes form in the blood and bone marrow.

Burkitt lymphoma is a fast growing B-cell cancer of the lymphatic system that occurs in distinct forms across different populations.

A small opening in the skull made with a surgical drill.

Pain that worsens with joint movement, along with local swelling and warmth, are hallmark features of bursitis, inflammation of a fluid-filled cushioning sac.

Unlike a fast-acting sedative it does nothing useful in the moment, and its benefit appears only after steady daily use.

A bypass is a surgical procedure that creates an alternate route for blood or other body fluid around a blocked or diseased structure.

A procedure in which a small amount of C-11 choline (a radioactive form of the vitamin choline) is injected into a vein.

An enzyme that is involved in many cell processes, such as cell division.

A protein involved in normal cell growth.

A substance that has been studied in the treatment of cancer and is being studied in the treatment of rheumatoid arthritis and certain skin conditions.

A protein on the surface of some cells that binds to stem cell factor (a substance that causes certain types of cells to grow).

A substance made by the pancreas.

A test used to help diagnose a type of pancreatic tumor called an insulinoma.

A test that measures the level of CA 19-9 in the blood.

A substance that may be found in high amounts in the blood of patients with certain types of cancer, including ovarian cancer.

CAB most often abbreviates a coronary artery bypass, surgery that reroutes blood around a blocked heart vessel, though the same letters also denote a community advisory board.

Cachexia is progressive muscle and fat wasting driven by an underlying chronic illness rather than by reduced food intake alone.

Cadmium is a naturally occurring heavy metal used in industry that can accumulate in the body and cause kidney damage with prolonged exposure.

Three older drugs given together on a fixed schedule, a breast cancer regimen now largely displaced by newer combinations.

A group of proteins that bind calcium and move it into cells.

Calcification is the deposit of calcium salts within soft tissue or organs, sometimes a normal effect of aging and sometimes a sign of disease.

A condition in which abnormal amounts of calcium salts are found in soft tissue, such as muscle.

A hormone formed by the C cells of the thyroid gland.

Bone acts as the bank: when blood levels dip, hormones withdraw calcium from the skeleton rather than let the level drift.

A test used to help diagnose a type of pancreatic islet cell tumor called a gastrinoma.

A drug used to lessen the toxic effects of substances that block the action of folic acid, especially the anticancer drug methotrexate.

A substance made from the flower of the marigold plant Calendula officinalis.