Medical terms - Letter H (page 14) | MedicalVocabulary.org

Human T-lymphotropic virus type I

(HTLV-I) A virus often referred to simply as the human T-lymphotropic virus (HTLV). HTLV-II stands for human T-lymphotropic virus type II, which is closely related to HTLV-I. HTLV-III is now known as the human…
Human T-lymphotropic virus type III

An obsolete term for the human immunodeficiency virus, now commonly called HIV
Humerus

The long bone in the arm which extends from the shoulder to the elbow.
Humidifier

Anything, usually a machine today, that adds moisture to the air
Humidifier fever

Fever: A form of sick building syndrome that usually develops on Monday or the first workday of the week. The hallmark of the disease is the sudden onset of fever. Other features may include muscle aches and pains and…
Humor

In medicine, humor refers to a fluid (or semifluid) substance. Thus, the aqueous humor is the fluid normally present in the front and rear chambers of the eye. The humors ran through an ancient theory that held that…
Humor, aqueous

In medicine, humor refers to a fluid (or semifluid) substance. Thus, the aqueous humor is the fluid normally present in the front and rear chambers of the eye. It is a clear, watery fluid that flows between and…
Humoral

Pertaining to elements in the blood or other body fluids. In medicine, humor refers to a fluid (or semifluid) substance. Thus, the aqueous humor is the fluid normally present in the front and rear chambers of the eye…
Humoralism

In medicine, humor refers to a fluid (or semifluid) substance. Thus, the aqueous humor is the fluid normally present in the front and rear chambers of the eye. The humors were part of an ancient theory that held that…
Humorism

In medicine, humor refers to a fluid (or semifluid) substance. Thus, the aqueous humor is the fluid normally present in the front and rear chambers of the eye. The humors were part of an ancient theory that held that…
Hump, dowager

An outward curvature of the vertebrae of neck, creating a hump at the back of the neck, once thought to be a characteristic deformity of older women. A dowager was a woman of high social rank whose husband was dead but…
Hunter syndrome

A genetic metabolic disorder that arises from deficiency of the enzyme iduronate sulfatase, resulting in tissue deposits of molecules called mucopolysaccharides. The characteristic features of Hunter syndrome include…
Huntingtin

The name of the gene responsible for Huntington disease (HD) and of the protein encoded by that gene. The molecular basis of HD is an increase in the length of a CAG triplet repeat (or 'polyglutamine') within the…
Huntington disease

Huntington disease: An hereditary disorder with mental and physical deterioration leading to death. Although characterized as an 'adult-onset' disease, it can affect children as well. Huntington disease describes an…
Hurler syndrome

An inherited error of metabolism in which there is deficiency of the enzyme alpha-L-iduronidase which normally breaks down molecules called mucopolysaccharides. Without the activity of this enzyme, there is an abnormal…
Hurricane

A regionally specific name for a strong tropical cyclone. The term hurricane applies in the North Atlantic Ocean, the Northeast Pacific Ocean east of the dateline, or the South Pacific Ocean east of 160E. Other terms…
Hurricane supplies kit

Hemolytic uremic syndrome.
HUS

Hemolytic uremic syndrome
Hyaline membrane disease

A respiratory disease of the newborn, especially the premature infant, in which a membrane composed of proteins and dead cells lines the alveoli (the tiny air sacs in the lung), making gas exchange difficult or…
Hyaluronic acid

Hyaluronic acid: A viscous slippery substance that lubricates the joints, maintains the shape of the eyeballs, and is a key component of connective tissue. On a more technical level, hyaluric acid is an…
Hybrid

The word 'hybrid' has a number of different biomedical meanings. In transmission genetics, a hybrid is the result of a cross between two genetically dissimilar parents. The offspring of unlike parents. If the parents…
Hybridization, fluorescent in situ

An important molecular cytogenetic method for identifying chromosomes and parts of chromosomes, deciphering chromosome rearrangements, and locating genes on chromosomes. 'Fluorescent' means emitting light that comes…
Hybridization, in situ

The use of a DNA or RNA probe to detect the complementary sequence. In situ hybridization is like all nucleic acid hybridization in being a technique in which single-stranded nucleic acids (DNA or RNA) are permitted to…
Hybridization, nucleic acid

A laboratory technique in which single-stranded nucleic acids (DNA or RNA) are allowed to interact so that complexes called hybrids are formed by molecules with similar, complementary sequences. Through nucleic acid…
Hybridoma

A cell hybrid resulting from the fusion of a cancer cell and a normal lymphocyte (a type of white blood cell). The hybridoma is immortal in the laboratory and makes the same products as its parent cells forever.
Hydatid disease, alveolar

A tumor that forms in the uterus as a mass of cysts resembling a bunch of grapes. Moles occur during the childbearing years. They do not spread outside of the uterus. However, a malignancy called choriocarcinoma may…
Hydatidiform mole

A tumor that forms in the uterus as a mass of cysts resembling a bunch of grapes. Moles occur during the childbearing years. They do not spread outside of the uterus. However, a malignancy called choriocarcinoma may…
Hydranencephaly

A condition in which the cerebral hemispheres of the brain are absent and replaced by sacs filled with cerebrospinal fluid. Usually the cerebellum and brainstem are formed normally. An infant with hydranencephaly may…
Hydrazine

Hydrazine sulfate, an alternative medicine that has been claimed to be a treatment for cancer. It has been used as a first-line agent in cancer therapy and as a treatment for cancer-related anorexia (loss of appetite)…
Hydrocarbon

An organic compound composed exclusively of hydrogen and carbon. All hydrocarbons have a carbon backbone with atoms of hydrogen attached to that backbone
Hydrocele

Accumulation of fluid in the coat around the testis. Small hydroceles tend to disappear by a year of age while larger hydroceles may persist and warrant surgery.
Hydrocephalus

Hydrocephalus: Hydrocephalus is an abnormal buildup of cerebrospinal fluid (CSF) in the ventricles of the brain. The fluid is often under increased pressure and can compress and damage the brain. Hydrocephalus can arise…
Hydrocephalus ex-vacuo

Hydrocephalus ex-vacuo: What is termed 'hydrocephalus ex-vacuo' occurs when there is damage to the brain caused by stroke or injury, and there may be an actual shrinkage of brain substance. Although there is more CSF…
Hydrocephalus, acquired

Hydrocephalus due to a postnatal cause, something that happened sometime after birth
Hydrocephalus, communicating

Hydrocephalus in which there is no obstruction to the flow of the cerebrospinal fluid (CSF). Specifically, there is no obstruction within the ventricular system of the brain or where the CSF passes into the spinal…
Hydrocephalus, congenital

Hydrocephalus present at birth
Hydrocephalus, Macewen sign of

A sign to detect hydrocephalus (and brain abscess). Percussion (tapping) on the skull at a particular spot (near the junction of the frontal, temporal and parietal bones) yields an unusually resonant sound in the…
Hydrocephalus, normal pressure

See: Normal pressure hydrocephalus
Hydrocephaly

Also known as hydrocephalus, this is an abnormal buildup of cerebrospinal fluid (CSF) in the ventricles of the brain. The fluid is often under increased pressure and can compress and damage the brain. Hydrocephalus can…
Hydrogen

The most plentiful element in the universe and one present in all organic compounds. Hydrogen is a gas with an atomic number of 1 and the symbol H. Two isotopes of hydrogen -- deuterium and tritium -- have been used as…
Hydrogen cyanide

See: Cyanide
Hydronephrosis

Hydronephrosis: Distention of the kidney with urine. Due to obstruction of urine outflow (for example, by a stone blocking the ureter, the tube going from the kidney to the bladder).
Hydrophobia

Gross edema (swelling), usually with anemia, of the fetus. It can be due to Rh blood group incompatibility, in which antibodies crossing the placenta from the mother destroy the red blood cells of the fetus. It can also…
Hydrops fetalis

Gross edema (swelling), usually with anemia, of the fetus. It can be due to Rh blood group incompatibility, in which antibodies crossing the placenta from the mother destroy the red blood cells of the fetus. It can also…
Hydrostatic weighing

See: Underwater weighing
Hydroxyapatite

Hydroxyapatite: A major component and an essential ingredient of normal bone and teeth. Hydroxyapatite makes up bone mineral and the matrix of teeth. It is hydroxyapatite that gives bones and teeth their rigidity…
Hydroxyapatite crystal disease

Hydroxyapatite crystal disease:The inflammation caused by hydroxyapatite crystals has been referred to as hydroxyapatite crystal disease. Hydroxyapatite is a major component and an essential ingredient of normal bone…
Hydroxytryptamine

See: Serotonin
Hydroxyurea

In Greek mythology, a goddess considered to be the guardian or personification of health. Hygieia was the daughter of Asclepius, the god of healing. In Greek, "hygieia" means health.
Hygieia

The science of preventive medicine and the preservation of health. From the name of Hygeia, the daughter of Asklepios, the Greek god of medicine (whose staff with entwined snake is the symbol of medicine). Asklepios…