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

Purpose: Human chorionic gonadotropin (HCG) has a stimulatory effect on tes ticular steroidogenesis and has been widely used for evaluating male Leydig cell function. However, considerable variability exists in the protocols f or HCG stimulation tests. In the most commonly used protocols HCG is admini stered daily for several days. We examine the circulating androgen response after I and 3-dose HCG regimens. Materials and Methods: We evaluated 77 prepubertal boys diagnosed with hypo spadias, cryptorchidisin 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 dihydrotestoste rone 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 re ference laboratory. Results: Nonstimulated testosterone levels were prepubertal in all groups. In the 1-dose groups post-stimulation testosterone was elevated 22 to 29-fo ld from baseline after a weight based and 34 to 35-fold after a body surfac e area based dose. Testosterone increased 20-fold baseline in the multi-dos e group. No significant differences were observed in 72 versus 96-hour horm one levels. Conclusions: Evaluating Leydig cell function by HCG stimulation is an impor tant adjunct to the diagnosis of various urological conditions. A single we ight 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 eva luation.