Category: H
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Herpetic whitlow
An intensely painful infection of the hand that causes blisters on one or more fingers, usually on the palm- side surface of the area of the finger closest to the fingertip. Herpetic whitlow is most often caused by herpes simplex virus 1, but may also be caused by herpes simplex virus 2. The infection is…
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Human rabies immune globulin
An immunizing agent. Rabies immune globulin is used along with rabies vaccine to prevent infection caused by the rabies virus. It works by providing antibodies needed to neutralize the rabies virus. The effects of rabies immune globulin will last long enough to provide protection until the body can produce its own antibodies against the rabies…
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Hot nodule
A growth on the thyroid gland that absorbs radioactive iodine during a diagnostic imaging procedure called radioactive iodine uptake. A hot nodule absorbs radioactive iodine because it is composed of functioning thyroid tissue, which attracts and holds iodine. This generally indicates that the tissue is not cancerous.
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Head lice
Small parasites that feed on blood from the scalp. Head lice are tiny gray insects (about the size of sesame seeds) that cause an intensely itchy scalp, are extremely contagious, and affect primarily schoolchildren. However, lice on a child can quickly spread to family members of all ages. Tiny parasites that feed on blood vessels…
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Hip joint replacement
A surgical procedure performed to replace the ball-and-socket joint of the hip with a specially designed prosthesis. A prosthetic hip joint replacement is implanted after removal of the diseased bone tissue and cartilage from the natural hip joint. Conditions that may lead to the need for this procedure include degenerative osteoarthritis, rheumatoid arthritis, injury, bone…
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Hypoaldosteronism
A condition resulting from a deficiency of the hormone aldosterone, which is normally produced by the adrenal cortex (the outer layer of the adrenal glands). Hypoaldosteronism produces biochemical changes in the body that result in a low level of sodium in the blood combined with an increased level of potassium. The condition is often associated…
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Hypnotic drugs
Drugs used to decrease the time needed to fall sleep. Hypnotic drugs prescribed to treat insomnia, or sleeplessness, include benzodiazepines, novel nonbenzodiazepine hypnotic drugs, antidepressants at low doses, the hormone melatonin, and chloral hydrate.
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Hypertensive hemorrhage
Bleeding caused by hypertension (high blood pressure). Hypertensive hemorrhage typically occurs in the blood vessels of the brain, is also known as cerebral hemorrhage, and can destroy the affected brain tissue. The severity of the hemorrhage and the symptoms it causes depend on the location and extent of the bleeding. Symptoms can come on suddenly…
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Hyperosmolar hypoglycemic nonketotic syndrome
A complication of diabetes mellitus that results from extremely high glucose (blood sugar) levels without the presence of ketones, a by-product of fat metabolism; abbreviated as HHNS. Sometimes wrongly called diabetic coma, HHNS is characterized by decreased consciousness, extreme dehydration, and very high blood glucose levels (often over 600 mg/dL). Symptoms may include increased thirst,…
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Hyperemesis gravidarum
Persistent intractable vomiting, usually beginning in early pregnancy, leading to weight loss and dehydration. This condition is uncommon and is associated with obesity and carrying twins. Hospitalization may be necessary to restore normal metabolic balance and prevent serious liver damage. Administration of intravenous fluids to the mother may be required to correct dehydration. There is…