Micropenis: an important early sign of congenital hypopituitarism.

Abstract

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 reportsCase 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

Penile Length and Testicular Volume in Newborns

“…[6]. Micropenis can also occur in children with LH receptor defect and defects in testosterone biosynthesis [7].…”

Normative Data of Penile Length for Term Chinese Newborns

“…Genes involved in the gonadal androgen production and in the peripheral androgen action may be relevant to the pathogenesis of micropenis. Also, micropenis is frequently present in a number of chromosomal or syndromal disorders such as Prader-Willi syndrome and Klinefelter syndrome, Noonan syndrome and Robinow syndrome [4] . Occasionally, micropenis may be a normal variant in the population, secondary to a transient androgen defect in late pregnancy [6] .…”

“…Diagnosis of micropenis in the newborn is important, as it may be the only manifestation of hypothalamic-pituitary axis disorder [1][2][3][4] . Fetal testosterone defi ciency is another common cause of micropenis.…”

Congenital adenohypophysis aplasia

“…If this stimulation is absent, a microphallus will occur. 8 Panhypopituitarism also occurs in certain conditions associated with midline cranio-facial abnormalities. The most striking conditions are those associated with holoprosencephaly.…”