Plasma testosterone in male puberty. II. hCG stimulation test in boys with hypospadia.

Plasma testosterone was determined by radioimmunoassay in 36 prepubertal boys with hypospadia prior to and 3 days after stimulation with 5000 IU of human chorionic gonadotrophin (hCG). As a control group, 30 boys of comparable age, predominantly with unilateral cryptorchidism, were studied. The increase in plasma testosterone levels after hCG was (median and range) 204 (83-393) ng/100 ml in the control group, whereas in the hypospadiac group a median increase of only 90 (33-272) ng/100 ml was found. The difference between the median testosterone levels after hCG stimulation in the two groups investigated is statistically highly significant (P less than 0.0001). After hCG stimulation, 13 out of the 36 boys with hypospadia did not reach the lowest stimulated testosterone level (87 ng/100 ml) found in the control group. It is concluded that a substantial portion of the aetiologically obscure cases of hypospadia are caused by an endocrine testicular insufficiency.