- Diminished production of thyroid hormone, leading to clinical manifestations of thyroid insufficiency, including low metabolic rate, tendency to weight gain, somnolence and sometimes myxedema. SYN: athyrea (1). [hypo- + G. thyreoeides, thyroid]- infantile h. can be due to endemic congenital goiter, nonendemic cases are usually due to defective thyroidal embryogenesis, defective hypothalamic-pituitary function, congenital defects in thyroid hormone synthesis or action, or intrauterine exposure to goitrogenic agents. SYN: Brissaud infantilism, congenital myxedema, dysthyroidal infantilism, hypothyroid dwarfism, hypothyroid infantilism, infantile myxedema, myxedematous infantilism.- secondary h. h. that arises as a consequence of inadequate thyrotropin secretion by the anterior pituitary gland.
* * *hy·po·thy·roid·ism -.iz-əm n deficient activity of the thyroid gland also a resultant bodily condition characterized by lowered metabolic rate and general loss of vigor
* * *n.subnormal activity of the thyroid gland. If present at birth and untreated it leads to cretinism. In adult life it causes mental and physical slowing, undue sensitivity to cold, slowing of the pulse, weight gain, and coarsening of the skin (myxoedema). The condition can be treated by administration of thyroxine.
* * *hy·po·thy·roid·ism (hi″po-thiґroid-iz-əm) deficiency of thyroid activity, characterized by decrease in basal metabolic rate, fatigue, and lethargy; if untreated, it progresses to myxedema. In adults it is more common in women than men, and in infants it can lead to cretinism. Called also athyria, athyroidism, athyroidosis, hypothyrosis, thyroprivia, and thyroid insufficiency.
Medical dictionary. 2011.