Growth hormone deficiency causes
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Differentiating Growth hormone deficiency from other Diseases |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Causes
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. Even congenital GH deficiency does not usually impair length growth until after the first few months of life. From late in the first year until mid teens, poor growth and/or shortness is the hallmark of childhood GH deficiency. Growth is not as severely affected in GH deficiency as in untreated hypothyroidism, but growth at about half the usual velocity for age is typical. It tends to be accompanied by delayed physical maturation so that bone maturation and puberty may be several years delayed. When severe GH deficiency is present from birth and never treated, adult heights can be as short as 48-58 inches (122-147 cm). Severe GH deficiency in early childhood also results in slower muscular development, so that gross motor milestones such as standing, walking, and jumping may be delayed. Body composition (i.e., the relative amounts of bone, muscle, and fat) is affected in many children with severe deficiency, so that mild to moderate chubbiness is common (though GH deficiency alone rarely causes severe obesity). Some severely GH-deficient children have recognizable, cherubic facial features characterized by maxillary hypoplasia and forehead prominence (said to resemble a kewpie doll).