Micropenis: an important early sign of congenital hypopituitarism.

Micropenis is an important sign in neonates, since it may be the only clue to the diagnosis of panhypopituitarism, a potentially lethal but eminently treatable condition. Case reports Case 1-A boy infant was delivered at 37 weeks' gestation after an uncomplicated pregnancy. Birth weight was 2200 g. He was asphyxiated and successfully resuscitated but remained hypotonic. Jaundice developed on the third day of life and persisted. At 3 weeks of age hypothyroidism was diagnosed (plasma thyroxine concentration 54 nmol/l (4-2 /ig/lOO ml), thyroid stimulating hormone concentration 8-5 mU/l). Despite thyroxine replacement he failed to thrive and developed abdominal distension and vomiting. Laparotomy showed milk curd obstruction of the small intestine, and postoperatively he was ventilated for three days. Twelve days later he collapsed and had a hypoglycaemic convulsion. For the next three months he was fed intravenously and became hypoglycaemic when attempts were made to restart oral feeds. At the age of 4 months the diagnosis of hypopituitarism was suggested because of his micropenis. During a hypoglycaemic episode (blood glucose concentration 10 mmol/l; 18 mg/100 ml) the plasma cortisol value was noted to be low at 100 nmoll1 (3-6 Ag/lOO ml) and concentrations of both plasma adrenocorticotrophic hormone (93 ng/l) and growth hormone (7-0 mU/l) were inappropriately low, consistent with hypopituitarism. The hypoglycaemia resolved rapidly with hydrocortisone replacement and did not recur. Growth hormone deficiency was confirmed by a glucagon stimulation test and appreciable penile growth occurred after three injections of depot testosterone. His jaundice, which had persisted despite thyroxine replacement, resolved after initiation of the hydrocortisone. Case 2-A boy infant (birth weight 3650 g) was delivered normally after an uncomplicated pregnancy. Shortly after birth he became hypothermic and hypoglycaemic and micropenis was noted. Three days after birth he became severely jaundiced with raised plasma transaminase activities, which persisted. Plasma thyroxine concentration was 16 nmol/1 (12 kg/lOO ml) without the appropriate thyroid stimulating hormone response (5-0 mU/l), indicating hypothyroidism of pituitary origin. Thyroid replacement was started but was inadequate. At 3 weeks of age he had several hypoglycaemic convulsions, and a normal blood glucose concentration could be maintained only Prenatal gonadotrophin deficiency may result in a small but normally formed penis with 10% dextrose infusion. His condition deteriorated with hypo-thermia, hypoglycaemia, hypotension, and jaundice. A presumptive diagnosis of hypopituitarism was made and after hydrocortisone and full thyroxine replacement his blood pressure and temperature rose. Hypoglycaemia was satisfactorily controlled only when …