Comparison of single versus multiple dose regimens for the human chorionic gonadotropin stimulatory test

Human chorionic gonadotropin (HCG) has a stimulatory effect on testicular steroidogenesis and has been widely used for evaluating male Leydig cell function. However, considerable variability exists in the protocols for HCG stimulation tests. In the most commonly used protocols HCG is administered daily for several days. We examine the circulating androgen response after 1 and 3-dose HCG regimens.

We evaluated 77 prepubertal boys diagnosed with hypospadias, cryptorchidism or micropenis. In 60 boys who underwent 1 dose of 100 IU/kg. or 5,000 IU/1.7 m.(2) HCG serum testosterone and dihydrotestosterone were sampled at 72 (28) and 96 (32) hours after injection, while in 17 who underwent 3 daily age adjusted doses hormone levels were determined on day 4. All blood specimens were obtained and injections were performed at 8:00 to 9:00 a.m. and all specimens were evaluated at the same endocrine reference laboratory.

Nonstimulated testosterone levels were prepubertal in all groups. In the 1-dose groups post-stimulation testosterone was elevated 22 to 29-fold from baseline after a weight based and 34 to 35-fold after a body surface area based dose. Testosterone increased 20-fold baseline in the multi-dose group. No significant differences were observed in 72 versus 96-hour hormone levels.

Evaluating Leydig cell function by HCG stimulation is an important adjunct to the diagnosis of various urological conditions. A single weight or body surface area based HCG dose with androgen measurement after 3 or 4 days is a practical, reliable and cost saving change in testicular evaluation.