Decreased immunoreactive inhibin and increased FSH levels in cryptorchidism after orchidopexy.

The blood FSH level is often high in patients with severe testicular disorders including cryptorchids. To examine whether inhibin is involved in the increase in FSH we measured immunoreactive inhibin, FSH, LH, and testosterone in 17 patients after orchidopexy. FSH was extremely high (20 mIU/ml or above) in 3 patients. The inhibin level was significantly lower (P < 0.01) in these 3 patients (6.47 +/- 2.19 IU/ml; mean +/- SEM) than in the other 14 patients (14.31 +/- 3.96 IU/ml). All 3 high-FSH patients had azoospermia. Testosterone and LH were normal in one of them. Even considering problems involved in the inhibin assay, the high FSH levels are considered to reflect reductions in the blood inhibin level due to Sertoli cell dysfunction. These findings suggest that inhibin plays an important role in the suppression of FSH at least in some patients after orchidopexy.