Testicular responsiveness to chronic human chorionic gonadotropin administration in hypogonadotropic hypogonadism

Steroidogenic responsiveness to long term hCG administration (1500 U three times a week for 23 months) was characterized in 8 males with hypogonadotropic hypogonadism (HH). During hCG treatment, testosterone (T), which was in the prepuberal range under basal conditions, rose considerably to the upper end of the normal range and remained at that level during the 23 months of observation. A 2.5-fold increase was observed in serum levels of 17 beta-estradiol (E2) an increment less than seen with T. The increment in 17 alpha-hydroxyprogesterone was also lower than that in T throughout the study; thus, the 17 alpha-hydroxyprogesterone to T ratio, despite continuous hCG administration, remained low. Serum androstenedione was slightly increased during hCG therapy. No significant changes were observed in serum levels of dehydroepiandrosterone. These data indicate that continuous long term hCG administration stimulated T levels in HH, with a relatively small change in E2. The kinetics of the T and E2 responses to 2000 U hCG, evaluated after 23 months of therapy, indicated that the testicular response was markedly reduced. No increment in T levels was observed at 24 h; the maximal response occurred at 48 h. This pattern of T response supports the idea that partial testicular desensitization occurs in HH patients receiving chronic treatment with hCG.