Mitchell E. Geffner, MD

Disclosures

Cancer Control. 2002;9(3) 

In This Article

Unique Features of Congenital Hypopituitarism

The most important presenting feature, and perhaps most common feature, of congenital hypopituitarism is hypoglycemia.[11] This occurs secondary to the presence of GH deficiency with or without associated ACTH deficiency (the latter leading to cortisol deficiency). Both GH and cortisol are counterregulatory ("anti-insulin") hormones that protect against hypoglycemia, especially during fasting. Without one or both, insulin acts in an unopposed fashion and, because of immaturity of other protective mechanisms against hypoglycemia in infants, this population is at an undue risk for low blood sugar. Thus, in infants (and sometimes in toddlers and older children) with unrecognized and/or untreated or undertreated hypopituitarism, hypoglycemia may often be recurrent and severe, potentially leading to permanent brain damage if not managed aggressively. The hypoglycemia usually resolves with replacement of GH and/or cortisol, although it may occasionally remain problematic in older children during stressful periods associated with reduced oral intake. An important caveat is that, in any term infant who develops hypoglycemia with no underlying risk factor (such as prematurity, intrauterine growth retardation, infant of a diabetic mother, etc), the diagnosis of hypopituitarism must be considered. Additionally, severe cortisol deficiency may result in presentation with hyponatremia (as cortisol is necessary for the action of anti-diuretic hormone [ADH, also known as vasopressin] to facilitate the excretion of free water by the kidneys) and/or outright shock due to its effects on blood pressure maintenance. If DI were present, shock with hypernatremia would be manifest.

Another unique feature of congenital hypopituitarism is the presence at birth of a microphallus (small penis) in some affected males. This may result from isolated GH deficiency or from combined GH and gonadotropin deficiencies (the latter leading to testosterone deficiency in the second and third trimesters and postnatally).[12] The microphallus may enlarge solely in response to treatment with GH, suggesting that GH has a critical role in penile growth at least in fetal and early postnatal life. Thus, some pediatric endocrinologists will initiate a 6-month trial of GH therapy alone to stimulate penile enlargement. If the response were inadequate, then a short course of low-dose testosterone therapy would follow. This can be in the form of 25 mg of long-acting testosterone enanthate given as four equally spaced intramuscular injections over a 12-week period. This approach is usually successful in equalizing penile size with that of other male infants and with few or no side effects. There are, however, other pediatric endocrinologists who would administer testosterone immediately, along with GH.

Lastly, some children with congenital hypopituitarism develop a unique, noninfectious form of hepatitis. The condition is suspected if there is liver enlargement and abnormal liver function tests (predominantly indicating cholestasis) and is confirmed by the presence of characteristic giant-cell transformation of hepatocytes as seen on biopsy.[13] The exact cause of this giant-cell hepatitis is unknown, and the condition usually remits on its own over the first few months of life without any permanent damage to the liver.

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