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.