hypocalcemia Lower-than-normal level of calcium in the blood, which makes the nervous system highly irritable, as evidenced by tetany (spasms of the hands and feet, muscle cramps, abdominal cramps, and overly active reflexes). Chronic hypocalcemia contributes to poor mineralization of bones, soft bones (osteomalacia), and osteoporosis. In children, hypocalcemia leads to rickets and impaired growth….
hypochondria The condition of being obsessed with imaginary medical complaints. A person with hypochondria tends to misinterpret minor physical changes as symptoms of major illness. It is closely related to, and may be a subtype of, obsessivecompulsive disorder. Treatment with antidepressant medication and/or cognitive behavioral therapy is often successful. See also obsessive-compulsive disorder.
hypochondroplasia A type of short-limb dwarfism, with shortening especially of the ends of the limbs. A child with hypochondroplasia usually has a prominent forehead, mildly shortened extremities and digits, limited range of motion at the elbows, and inward curvature of the lower back. Diagnosis is made through physical examination and X-rays. Hypochondroplasia is inherited in…
hypoglossal nerve The twelfth cranial nerve, which supplies the muscles of the tongue.
hypoglossal neuropathy Disease of the hypoglossal nerve. Paralysis of the hypoglossal nerve affects the tongue, making speech sound thick and causing the tongue to deviate toward the paralyzed side. In time, the tongue diminishes in size (atrophies).
hypoglycemia Low blood sugar (glucose). Hypoglycemia may be associated with symptoms such as anxiety, sweating, tremor, palpitations, nausea, and pallor. Hypoglycemia also starves the brain of glucose energy, which is essential for proper brain function. Lack of glucose energy to the brain can cause symptoms ranging from headache, mild confusion, abnormal behavior, loss of consciousness,…
hypokalemia Low potassium in the blood. Hypokalemia is commonly caused by conditions that lead to loss of potassium through the gastrointestinal tract such as vomiting, diarrhea, impaired kidney function, and use of diuretic medications. Symptoms may include fatigue, weakness, muscle cramping, and arrythmias of the heart.
hypomagnesemia Low magnesium in the blood, which can occur due to inadequate intake or impaired intestinal absorption of magnesium. Hypomagnesemia is often associated with low calcium (hypocalcemia) and low potassium (hypokalemia). It causes increased irritability of the nervous system with tetany (spasms of the hands and feet, muscular twitching and cramps, spasm of the larynx,…
hypomania A condition similar to mania but less severe. The symptoms include elevated mood, increased activity, decreased need for sleep, grandiosity, racing thoughts, and the like. However, hypomanic episodes differ in that they do not cause significant distress or impair one’s work, family, or social life to the extent that manic episodes do. Hypomania is…
hyponatremia Low sodium in the blood. Hyponatremia can be caused by many conditions and when severe can lead to confusion and seizures.
hypophosphatemia A lower-than-normal level of phosphate in the blood. Hypophosphatemia can be associated with a number of conditions including bone diseases and hormone conditions. Symptoms occur only when hypophosphatemia is very severe and include muscle weakness that may progress to coma and death.
hypopigmentation Lack of color in the skin or eyes. Hypopigmentation is characteristic of the various forms of albinism and of several genetic diseases. See albinism; Hermansky-Pudlak syndrome.