Growth hormone deficiency
Growth hormone deficiency is the medical condition of inadequate production of growth hormone (GH) and its effects on children and adults. Growth hormone, also called somatotropin, is a polypeptide hormone which stimulates growth and cell reproduction. See separate articles on GH physiology and GH treatment. more...
Deficiency of GH produces significantly different problems at various ages. In newborn infants the primary manifestations may be hypoglycemia or micropenis. In later infancy and childhood, growth failure may be major effect. Adults with growth hormone deficiency may have diminished lean body mass and poor bone density and a number of physical and psychological symptoms.
GH deficiency can be congenital or acquired in childhood or adult life. It can be partial or complete. It is usually permanent, but sometimes transient. It may be an isolated deficiency or occur in association with deficiencies of other pituitary hormones.
GH deficiency is treated by growth hormone replacement.
The term hypopituitarism is often used interchangeably with GH deficiency by endocrinologists but more often denotes GH deficiency plus deficiency of at least one other anterior pituitary hormone. When GH deficiency (usually with other anterior pituitary deficiencies) is associated with posterior pituitary hormone deficiency (usually diabetes insipidus) the condition is termed panhypopituitarism.
HGH also refers to human growth hormone but this older abbreviation has begun to develop paradoxical connotations (see fuller discussion of HGH in GH treatment and HGH quackery).
Causes of GH deficiency
There are many causes of GH deficiency. Some examples include:
- mutations of specific genes (e.g., GHRHR, GH1)
- congenital malformations involving the pituitary (e.g., septo-optic dysplasia, posterior pituitary ectopia)
- damage to the pituitary from incracranial disease (e.g., hydrocephalus),
- intracranial tumors in or near the sella turcica, especially craniopharyngioma,
- damage to the pituitary from radiation therapy to the head for leukemia or brain tumors,
- surgery in the area of the pituitary,
- autoimmune inflammation (hypophysitis),
- severe head trauma,
- ischemic or hemorrhagic infarction from low blood pressure (Sheehan syndrome) or hemorrhage pituitary apoplexy.
Many cases of isolated growth hormone deficiency (IGHD) recognized in childhood are idiopathic. IGHD has been reported to affect about 1 in 4000 children, but IGHD is difficult to distinguish from other causes of shortness such as constitutional delay, and the true incidence is unsettled.
Severe prenatal deficiency of GH, as occurs in congenital hypopituitarism, has little effect on fetal growth. However, prenatal and congenital deficiency can reduce the size of a male's penis, especially when gonadotropins are also deficient. Besides micropenis, additional consequences of severe deficiency in the first days of life can include hypoglycemia and exaggerated jaundice (both direct and indirect hyperbilirubinemia). Female infants will lack the microphallus of course but may suffer from hypoglycemia and jaundice.
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