Glossary of Medical Terms -Medical, Pathology and Laboratory Medicine


ACTH (Adrenocorticotropic hormone) – Hormone produced by the pituitary gland. It stimulates adrenal glands to secrete the hormones they produce, including cortisone and cortisol. 

ACTH (Adrenocorticotropic hormone) deficiency – Too little ACTH produced by the pituitary gland; often the result of a pituitary tumor. Symptoms include weakness, fatigue and gastrointestinal disturbances. 

AIDS (Acquired Immune Deficiency Syndrome) – Major failure of body’s immune system (immunodeficiency disease). It decreases body’s ability to fight infection and suppress multiplication of abnormal cells, such as cancer cells. See Immunodeficiency disease. Caused by a sexually transmitted virus, contaminated blood or via the placenta to a fetus of an infected mother. 

Abell-Kendall modification – Modification of a lab test developed by Drs. Abell and Kendall.

Abruptio placenta – Separation of the placenta from the uterus during the last trimester of pregnancy.

Absolute Neutrophil Count (ANC) also called “absolute granulocyte count” – amount of white blood cells presents in the blood that are able to fight infection.

Abscess – Swollen, inflamed, tender area of infection filled with pus.

Achalasia – Condition of the esophagus that disrupts normal swallowing.

Acid-base imbalance – Imbalance that occurs when body retains too much acid or too much base.

Acidosis – Pathologic condition resulting from accumulation of too much acid in the body.

Acidosis, metabolic – Too much acid in the body due to loss of base.

Acidosis, respiratory – Too much acid in the body due to accumulation of excess carbon dioxide.

Acromegaly – Condition that afflicts middle-aged people. Characterized by a gradual, marked enlargement of the bones of the face, jaw and extremities. Caused by overproduction of growth hormone by pituitary gland.

Acute – Beginning suddenly. Severe but of short duration.

Acute intermittent porphyria (AIP) – Disease of porphyrin metabolism. Symptoms include recurrent attacks of abdominal pain, gastrointestinal symptoms, neurological disturbances and an excess of porphobilinogen in the urine.

Acute pulmonary edema – Set of dramatic, life-threatening symptoms, including extreme shortness of breath, rapid breathing, anxiety, cough, bluish lips and nails, and sweating. Usually caused by congestive heart failure. See Congestive heart failure.

Addison’s disease (Adrenal insufficiency) – Condition caused by inactive or underactive adrenal glands. Symptoms include weakness, low blood pressure, behavior changes, abdominal pain, diarrhea, appetite loss and brown skin.

Adenocarcinoma – Any of a large group of cancerous tumors of a gland or gland tissue.

Adenoma – Benign tumor of glandular cells. May cause excess hormone secretion by the affected gland.

Adhesions – Small strands of fibrous tissue that cause organs in the abdomen and pelvis to cling together abnormally, creating a risk of intestinal obstruction.

Adrenal – Pertaining to one or both glands located adjacent to the kidneys. These glands secrete many hormones, including adrenalin, and play an important part in the body’s endocrine system.

Adrenal cortex – Outer layer of the adrenal gland. Secretes various hormones including cortisone, estrogen, testosterone, cortisol, androgen, aldosterone and progesterone.

Adrenal hyperplasia – Abnormal increase in the number of normal cells in the adrenal gland(s).

Adrenal insufficiency – See Addison’s disease.

Adrenal medulla – Middle part of the adrenal gland. Secretes epinephrine (adrenalin) and norepinephrine.

Adrenal medulla tumors (Pheochromocytoma) – Tumors of the medulla, an inner layer of the adrenal gland, called pheochromocytomas. Tumors are rare and secrete norepinephrine and epinephrine. They are characterized by episodes of hypertension, headache, palpitations, sweating and apprehension.

Adrenocortical hyperplasia – Increase in the number of cells of the adrenal cortex. Adrenal cortex secretes cortisol, androgens and aldosterone. Increased production of any or all of these hormones may result in a variety of disorders, such as Cushing’s syndrome and hypertension.

Adrenocorticotropic hormone deficiency – Not enough ACTH is produced by the pituitary gland.

Adrenoleukodystrophy – Disturbance in brain substance caused by abnormal function of the adrenal gland.

Agglutination – Clumping together.

Ahaptoglobulinemia – Without haptoglobin in the blood. Condition is often seen with hemolytic anemia, severe liver disease and infectious mononucleosis. See Anemia, hemolytic; infectious mononucleosis.

Alcohol cardiomyopathy – Disease of the myocardium (muscle layer) of the heart, due to chronic alcoholism. Results in enlargement of the heart. Heart muscle is weakened and cannot pump blood efficiently.

Alcoholic polymyopathy – Disease affecting several muscles simultaneously. Caused by alcoholism.

Aldosteronism, primary – Overproduction of aldosterone, which is secreted by adrenal glands. Caused by adrenal hyperplasia (increase in number of adrenal cells) or a tumor of the adrenal gland (Conn’s syndrome). Symptoms may include hypertension, muscle weakness or cramping, kidney disease and abnormal heart rhythm.

Alkalosis, metabolic – Abnormal condition in which body fluids are more alkaline than normal. Can result from loss of acid from prolonged vomiting or excess intake of bicarbonate.

Alkalosis, respiratory – abdominal pain, diarrhea, appetite loss and brown skin. Abnormal condition when body fluids are more alkaline than normal. Caused by conditions that decrease the level of carbon dioxide in the blood, such as breathing too rapidly or congestive heart failure. See Congestive heart failure.

Allogeneic Transplant – a transplant using a human donor who has bone marrow that is a genetic match to the recipient.

Alveolar edema – Swelling of the smallest branches of the bronchial tubes (alveoli).

Ambiguous genitalia – External genitals that are not normal for the sex.

Amblyopias – Reduced vision in an eye that appears to be normal when examined with an ophthalmoscope (an instrument used to examine the interior of the eye). Sometimes associated with strabismus. May also be caused by certain toxins.

Amenorrhea – There are two categories of amenorrhea. In primary amenorrhea, menstruation has not begun in a young woman who has passed puberty and is at least 16 years old. Cause is usually unknown. Possible causes may include eating disorders, psychological disorders, endocrine disorders, congenital abnormality in which female organs are absent or abnormally formed, or participation in very strenuous athletic activities. In secondary amenorrhea, there is cessation of menstruation for at least 3 months in a woman who has previously menstruated. Causes include pregnancy, breast feeding, eating disorders, endocrine disorders, psychological disorders, menopause (usually 35 years of age or older), surgical removal of uterus or ovaries, or very strenuous athletic activities.

Amine – Organic chemical compound containing nitrogen.

Amino acids – Organic chemical compounds. They are the chief components of all proteins. The body contains at least 20 amino acids; 10 are ESSENTIAL. The body doesn’t make or form these acids, so they must be acquired through diet.

Ampulla of Vater – Enlarged area where the pancreatic duct and common bile duct come together before entering the section of small intestine.

Amyloid – Starchy substance.

Amyloidosis – Disease in which a waxy, starch like, translucent material accumulates in tissues and organs, impairing function. Cause is unknown and is currently incurable. If kidneys are involved, kidney dialysis or a kidney transplant may be part of the treatment.

Amyotrophic lateral sclerosis (ALS) – Progressive breakdown of spinal cord cells, resulting in gradual loss of muscle function. Not contagious or cancerous.

Anaphylaxis (Allergic shock) – Severe, life-threatening allergic response to medications or other allergy-causing substances.

Androgenic arrhenoblastoma – Ovarian tumor in which cells resemble those in male testes; they secrete male sex hormone. Causes appearance of male secondary sex characteristics in a woman, such as a husky, deep-pitched voice, excessive body hair and enlarged clitoris.

Andrenogenital syndrome – Endocrine disorder resulting from adrenocortical hyperplasia. See Adrenal hyperplasia. Less than normal amounts of cortisol and greater than normal amounts of androgens are produced. This results in precocious puberty in boys and masculinization of the external genitals in girls. Usually a congenital disorder.

Anemia – Condition in which the number of red blood cells or hemoglobin (oxygen carrying substance in blood) are inadequate.

Anemia, aplastic – Serious disease characterized by decreased bone marrow production of all blood cells. Symptoms may include paleness, weakness, frequent infection, spontaneous bleeding from the nose, mouth, gums, vagina, rectum, brain and other sites, unexplained bruising, and ulcers in the mouth, throat or rectum. May be caused by disease in the bone marrow or destruction of the bone marrow by
exposure to certain chemicals, anticancer drugs, immunosuppressive drugs or antibiotics. Cause is sometimes unknown. Curable if cause can be identified and treated successfully. If response to treatment is poor, complications of uncontrollable infections and bleeding may be fatal.

Anemia, autoimmune hemolytic – Anemia due to the breakdown of an individual’s blood cells by his own serum. Exact cause is unknown and still under investigation. See Serum.

Anemia, chronic hemolytic – Anemia caused by an inherited disorder, such as hereditary spherocytosis, G-6-PD deficiency, sickle cell anemia or thalassemia. Currently no cure is known. See Anemia; hemolytic anemia; G-6-PD deficiency; sickle cell anemia; thalassemia.

Anemia, diserythropoietic – Any anemia caused by a disorder that diminishes the body’s normal ability to produce red blood cells.

Anemia, hemolytic – Anemia due to the premature destruction of mature red blood cells. Bone marrow cannot produce red blood cells fast enough to compensate for those being destroyed.

Anemia, hypochromic – Any of a large group of anemias characterized by a decreased concentration of hemoglobin in red blood cells.

Anemia, hypoplastic – Anemia characterized by decreased bone marrow production of red blood cells.

Anemia, idiopathic acquired hemolytic – Anemia characterized by a shortened lifespan of red blood cells. Cause is unknown, but it is not hereditary.

Anemia, iron deficiency – Decreased number of circulating red blood cells or insufficient hemoglobin in the cells. Caused by inadequate supplies of iron.

Anemia, macrocytic – Blood disorder characterized by abnormal presence of large, fragile red blood cells. Mean corpuscular hemoglobin (MCH) and mean corpuscular volume (MCV) are increased. Often the result of folic acid and vitamin-B12 deficiency.

Anemia, megaloblastic (Folic acid deficiency) – Anemia caused by folic acid deficiency. Often accompanied by iron deficiency anemia.

Anemia, microcytic – Any anemia characterized by abnormally small red blood cells, usually associated with chronic blood loss or nutritional anemia, such as iron deficiency anemia. See Anemia, iron deficiency; anemia, megaloblastic; red cell indices.

Anemia, non-spherocytic hemolytic – Inherited disorder of red blood cells in which shortened red cell survival is associated with membrane defects, unstable hemoglobin and intracellular defects.

Anemia, pernicious – Anemia caused by inadequate absorption of vitamin B12.

Anemia, pyridoxine-responsive – Decreased red blood cells in circulation, which increase to normal with pyridoxine treatment.

Anemia, sickle cell – Severe, incurable anemia that occurs in people who have an abnormal form of hemoglobin in their blood cells. It is an inherited disease.

Anemia, sickle cell trait – See Sickle cell trait.

Anemia, sideroblastic- A special type of anemia in which the bone marrow deposits iron prematurely into red blood cells. These cells do not transport oxygen to the body as efficiently as normal cells.

Anencephaly – Absence of the brain.

Aneuploidy – Any variation in chromosome number that involves individual chromosomes and not entire sets of chromosomes. There may be fewer chromosomes, as in Turner’s syndrome, or more chromosomes, as in Down’s syndrome. See Turner’s syndrome; Down’s syndrome. Abnormal traits vary depending on which set of chromosomes is involved.

Aneurysm – Abnormal enlargement or ballooning of an artery. Caused by a weak artery wall.

Angina (Angina pectoris) – Chest pain or pressure usually beneath the sternum (breastbone). Caused by inadequate blood supply to the heart. Often brought on by exercise, emotional upset or heavy meals in someone who has heart disease.

Angina pectoris – See Angina.

Angiodysplasia – Small blood vessel abnormalities.

Angioedema (Angioneurotic edema; hives) – Allergic disorder characterized by skin changes with raised areas, redness and itching.

Angiomas – Benign tumor made up of blood vessels or lymph vessels. Most are congenital.

Anion gap – Measure combining laboratory analysis of sodium, chloride and bicarbonate. A quick, noninvasive calculation.

Ankylosing spondylitis – Chronic, progressive disease of the joints, accompanied by inflammation and stiffness. Characterized by a BENT-FORWARD posture caused by stiffening of the spine and support structures. Cause is unknown but may be due to genetic changes or an autoimmune disorder. Currently considered incurable, although symptoms can be relieved or controlled. There have been cases of unexplained recovery.

Anorectal abscess – Abscess occurring in the rectum (last segment of the large intestine) and anus (opening of the rectum on the body surface).

Anorexia – Loss of appetite.

Anorexia nervosa – Extremely complicated personality disorder, chiefly in young women, characterized by aversion to food, obsession with weight loss and various other symptoms.

Anovulation – Failure of ovaries to produce, mature or release eggs. Antibodies – Proteins created in blood and body tissue by the immune system to neutralize or destroy sources of disease.

Antibiotics – a group of medicines used to prevent or treat infections.

Antibody – a protein that helps the body fight foreign substances (antigens) in the body, such as bacteria, fungi and viruses.

Antigens – A foreign substance that stimulates the formation of antibodies in the body (produced by the immune system) neutralize or destroy.

Anti-lipemic (Anti-lipidemic) – Of or pertaining to a regimen, diet, agent or drug that reduces the amount of fat or fat-like substances (lipids) in the blood.

Antinuclear antibody (ANA) – Substance that appears in the blood indicating presence of an autoimmune disease. See Autoimmune disease.

Aortic-valve stenosis – Heart abnormality characterized by narrowing or stricture of the aortic valve due to a congenital malformation of the valve or fusing of segments of the valve, such as from rheumatic fever. See Rheumatic fever. This results in obstruction of blood flow out of the heart into the aorta; heart cannot pump effectively. Signs of the disease include intolerance for exercise, heart pain and heart murmur. Treatment usually includes surgery to repair the defective valve.

Aortoiliac occlusive disease – Complete or partial blocking of the lower part of the aorta as it enters the leg, at the level of the groin.

Apheresis – a blood-separating procedure in which blood is removed from a patient, sent through a special machine (where cells are separated, and some are removed) and the remainder are returned to the patient

Aplastic anemia – a blood disorder in which the bone marrow is deficient in producing red blood cells, white blood cells and platelets.


Apnea – Absence of spontaneous breathing.

Appendicitis – Inflammation of the vermiform appendix (small tube that extends from the first part of the large intestine). Affects 1 in 500 people every year. Symptoms may include right lower abdominal pain, nausea, vomiting, constipation or diarrhea, and fever. Treatment includes prompt surgical removal of the appendix. Delay in surgery usually results in a ruptured appendix and peritonitis, which can be fatal.See Peritonitis.

Arachnoiditis – Inflammation of the arachnoid membrane, a thin, delicate membrane enclosing the brain and spinal cord.

Arginosuccinic aciduria – Presence of arginosuccinic acid in the urine. This is an inborn error of metabolism and causes mental retardation.

Arrhythmias – Occasional or constant abnormalities in the rhythm of the heartbeat.

Arterial-occlusive disease – Total or partial blockage of any large artery.

Arteriosclerosis – Common disorder of the arteries characterized by thickening, loss of elasticity and calcification of artery walls. Results in decreased blood supply to the brain and lower extremities. Typical signs include pain on walking, poor circulation in feet and legs, headache, dizziness and memory defects. Condition often develops with aging or with nephrosclerosis, scleroderma, diabetes and hyperlipidemia.See Diabetes; nephrosclerosis; scleroderma.

Arteriovenous malfunction – Problem at the junction of an artery and vein at the capillary level.

Arthritis – Inflammatory condition of the joints, characterized by pain and swelling. Also see Rheumatoid arthritis.

Ascites – Accumulation of serous fluid in the abdominal cavity. It contains large amounts of protein and electrolytes. May be a complication of cirrhosis, congestive heart failure, nephrosis, cancer, peritonitis or various fungal and parasitic diseases. See Cirrhosis; congestive heart failure; nephrosis; cancer; peritonitis.

Asphyxia – Loss of consciousness due to too little oxygen and too much carbon dioxide in the blood. If not corrected, it results in death.

Aspiration (of marrow) – the removal of marrow from the cavities in large bones by suction through a needle.

Asthma – Chronic disorder with recurrent attacks of wheezing and shortness of breath.

Astigmatism – Visual impairment caused by abnormal eye shape.

Astrocytomas – Brain tumor composed of neuroglial cells (one of the two main kinds of cells that make up the nervous system). Usually grows slowly, but often a highly malignant tumor, called a glioblastoma, develops inside the astrocytoma. Complete surgical removal of an astrocytoma may be possible early in the development of the tumor, but not after it has invaded surrounding tissue.

Ataxia-telangiectasia – Severe, hereditary, progressive disease beginning in early childhood. It results in lesion of a blood vessel formed by dilation of a group of small blood vessels (telangiectasias) of the eyes and skin, failure of muscles to coordinate (ataxia), including abnormal eye movements and immunodeficiency. This probably accounts for increased susceptibility to infections. Usually results in shortened life span.

Atopic dermatitis – Chronic inflammatory disease of the skin; often associated with other allergic disorders that affect the respiratory system, such as asthma or hay fever. See Asthma. Cause is unknown, but may be an inherited or an immune system deficiency disease. Symptoms include itchy rash in skin creases, dry, thickened skin in affected areas, uncontrolled scratching and fatigue from loss of sleep due to intense itching. Flare-ups and remissions can occur throughout life. Treatment may relieve

Atria – Chamber allowing entrance into another structure. Usually refers to ATRIA of the heart, which allows transmission of blood into the larger chambers of the heart called the ventricles.

Atrial fibrillation – Completely irregular heartbeat rhythm. In this case, it occurs in the top chambers of the heart. Sometimes it causes no symptoms. Sometimes the person may feel weak, dizzy or faint. Often, a normal heart rhythm can be restored with medication or an electric shock (electro cardioversion).

Atrophy – Wasting away; diminishing in size such as a cell, tissue, organ or part. May result from disease, lack of use, aging or other influences.

Autoimmune – Response directed against the body’s own tissue.

Autoimmune disease – Disease in which the immune system produces antibodies that attack the body’s own tissues.

Autoimmune hemolytic anemia – See Anemia, autoimmune hemolytic.
Autoimmune thyroid disease – See Grave’s disease.

Autologous Transplant – a transplant in which a patient’s own blood stem cells are collected, frozen and then returned to the patient at a later date.


Blood Cells – cells formed in the bone marrow that make up blood.

Red Blood Cells (erythrocytes; RBCs) – cells that carry oxygen throughout the body (measured by the hematocrit or HCT)

Bone Marrow Harvest – a procedure in which bone marrow is taken from the pelvic bone (hip area) for use in a transplant.

Bone Marrow Transplant – a process in which a patient’s bone marrow is destroyed by chemotherapy and/or radiation therapy and then replaced by previously harvested stem cells from a donor or the patient.


Central Line Catheter – semi-permanent intravenous catheter that is inserted into the large blood vessels that enter into the heart. It can stay in you for many weeks – months often.

Chemotherapy – drugs used to treat cancer, either by destroying abnormal (cancer) cells or by slowing their growth.

Complete Blood Count – a blood test that determines the number of red blood cells, white blood cells and platelets in the blood.

Conditioning – a combination of chemotherapy drugs, and sometimes radiation, given a few days prior to transplant to eliminate cancer cells and destroy the immune system.

Cytomegalovirus – a virus that can cause flu-like symptoms in patients with normal immunity, and more severe problems (lung infections, liver problems and intestinal problems) in patients with suppressed immune systems.

Tab Content
Tab Content
Tab Content
Tab Content
Tab Content
Tab Content
Tab Content
Tab Content
Tab Content
Tab Content
Tab Content
Tab Content
Tab Content
Tab Content
Tab Content
Tab Content
Tab Content
Tab Content
Tab Content
Tab Content
Tab Content
Tab Content
Tab Content