Dictionary

hyperplasia, endometrial A condition characterized by overgrowth of the lining of the uterus. This is considered a precancerous condition.

hypersomnia Excessive sleepiness in which a person has trouble staying awake during the day or exhibits prolonged nighttime sleep. People who have hypersomnia can fall asleep at any time—for example, at work or while they are driving—and they may have other sleep-related problems. Causes include narcolepsy, sleep deprivation, neurological or other medical conditions, obesity, genetic…

hypertension See high blood pressure.

hypertension, benign intracranial See pseudotumor cerebri.

hypertension, pulmonary High blood pressure in the pulmonary arteries. This elevated blood pressure can lead to severe shortness of breath and death. Lung transplantation is considered in severe cases that are unresponsive to treatments.

hyperthermia Overheating of the body, possibly due to extreme weather conditions. Unrelieved hyperthermia can lead to collapse and death, particularly in the elderly. Hyperthermia can be prevented in many cases through use of air conditioning and ventilation, as well as by ensuring that vulnerable persons drink extra water. In emergency cases of hyperthermia, injections of…

hyperthermia, malignant A rare inherited disease that causes a rapid rise in body temperature and muscle rigidity when a person undergoes general anesthesia. Succinyl choline and halothane are the two drugs most associated with the condition. The result can be destruction of muscle tissue, kidney failure, and death may occur. The propensity to malignant hyperthermia…

hyperthyroid Having an excessive amount of thyroid hormone resulting from an overactive thyroid gland or from taking too much thyroid hormone. Symptoms of hyperthyroidism can include increased heart rate, weight loss, depression, and cognitive slowing. Treatment can include medications, the use of radioactive iodine, thyroid surgery, or a reduction in the dose of thyroid hormone.

hymen A thin membrane that may completely or partially cover the vaginal opening before first sexual intercourse but that usually disappears before puberty.

hyoglossus The muscle that permits the tongue to be held on the floor of the mouth.

hyper- Prefix meaning high, beyond, excessive, or above normal, as in hyperglycemia (high sugar in the blood) and hypercalcemia (high calcium in the blood). The opposite of hyper- is hypo-.

hyperactivity A higher-than-normal level of activity. An organ can be described as hyperactive if it is more active than is usual. Behavior can also be described as hyperactive. See also attention deficit hyperactivity disorder.