Dictionary

hypospadias A birth defect in which the urethra opens on the underside of the penis or below the penis. Treatment involves surgery to repair and reconstruct the urethra.

hypoplastic left heart syndrome A form of congenital heart disease in which the whole left half of the heart, including the aorta is underdeveloped (hypoplastic). Blood returning from the lungs has to flow through an opening in the wall between the upper chambers of the heart (an atrial septal defect). The right ventricle pumps blood…

hypoplasia of the thymus and parathyroids See DiGeorge syndrome.

hypoplasia Underdevelopment or incomplete development of a tissue or an organ. For example, hypoplasia of the enamel of the teeth indicates that the enamel coating is thinner than normal or missing in some but not all areas. Hypoplasia is less drastic than aplasia, where there is no development of a tissue or an organ at…

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.

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.

hyponatremia Low sodium in the blood. Hyponatremia can be caused by many conditions and when severe can lead to confusion and seizures.

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…

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,…

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.

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,…

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).