Responses of serum testosterone levels to human chorionic gonadotrophin stimulation in patients with Klinefelter's syndrome after long-term androgen replacement therapy.

Responses of serum testosterone levels to repeated daily injections of 5000 IU hCG for 4 days were studied in 24 patients with Klinefelter's syndrome. Eighteen patients were untreated, and 8 had been given previous treatment with depot testosterone 100 mg intramuscularly every 2-3 weeks for an average duration of 4.7 years. Among them, 4 patients were examined both before and after the therapy. The hCG test was performed at least 2 weeks (0.5-12 months) after the last injection of depot testosterone in the treated patients. Mean basal testosterone level of the treated patients, 139 +/- 98 ng/dl (Mean +/- SD), was not significantly different from that of the untreated patients, 172 +/- 110 ng/dl. Maximum stimulated testosterone level in the treated patients, 170 +/- 107 ng/dl (P less than 0.05). These results suggest that long-term androgen administration may decrease the functional reserve of Leydig cells in patients with Klinefelter's syndrome.