Serum inhibin levels before and after gonadotropin stimulation in cryptorchid boys under age 4 years.

We evaluated eleven cryptorchid boys under four years of age to determine the usefulness of serum inhibin as a marker of seminiferous tubule dysfunction. Serum testosterone, inhibin, LH and FSH concentrations were measured by RIA before and after 6 weeks of human chorionic gonadotropin plus human menopausal gonadotropin therapy, and bilateral testicular biopsies were performed at orchiopexy. Hormonal results from the cryptorchid group were compared to those from an age-matched control group. Basal LH and testosterone levels were similar in the two groups. Cryptorchid boys had lower basal inhibin and higher FSH levels than controls. After gonadotropin treatment the inhibin/FSH ratio was lower in cryptorchid than control children, suggesting the presence of seminiferous tubule damage (p = 0.002). Normal numbers of spermatogonia were seen in 6/9 scrotal and in 1/13 cryptorchid testes. The peak of inhibin was positively correlated to the number of spermatogonia (r = 0.68; p = 0.02). We conclude that basal and stimulated inhibin concentrations, as well as basal and stimulated inhibin/FSH ratio, provide additional information on seminiferous tubule function in cryptorchid boys and can be useful to evaluate Sertoli cell function in these patients.