[Kinetics of the testicular steroidogenic response to stimulation with placental gonadotropin in the prepuberal boy].

The kinetics of the plasma level responses of steroid hormones to a single injection of human chorionic gonadotrophin (hCG) (100 Ul/kg) was studied for one week in 7 prepubertal boys. Plasma testosterone levels progressively increased up to 8.22 +/- 1.33 nmol/l, usually at the 100th hour. The kinetics of dihydrotestosterone was quite similar. On the other and, progesterone, 17 alpha-hydroxyprogesterone and delta 4-androstenedione did not change significantly; 17 beta-estradiol slightly increased 5 to 7 days later. This profile of response is deeply different from those observed in adults, in whom are observed an early response (24 hrs) of 17 alpha-hydroxyprogesterone and estradiol and a two-phase response of testosterone. These results show that the hCG-induced steroidogenic desensitization is present only in patients previously exposed to a certain level of gonadotrophic stimulation (endogenous or exogenous).