General Medical Information

Deficiencies in Testosterone Biosynthesis

Joe Leigh Simpson

Male pseudohermaphroditism may result from deficiencies of 17a-hydroxylase, 3b-ol-dehydrogenase, or 17-ketosteroid reductase 17,20-desmolase. These enzymes are required to convert cholesterol to pregnenolone (congenital adrenal lipoid hyperplasia). Deficiencies of 21-hydroxylase or 11b-hydroxylase, the most common causes of female pseudohermaphroditism, do not cause male pseudohermaphroditism. Males (46,XY) show precocious masculinization.

Adrenal biosynthetic defects should be suspected if levels of testosterone or its metabolites are decreased. Diagnosis of the various conditions, to be discussed later, is not difficult in older children, but detection may be difficult during infancy because neonatal testosterone levels are physiologically low. Provocative tests (i.e., human chorionic gonadotropin stimulation) may facilitate diagnosis.