INHIBIN AND STEROID-RESPONSE TO TESTICULAR STIMULATION WITH PURE FSH (METRODIN) IN INFERTILE MEN WITH UNILATERAL CRYPTORCHIDISM

Static measurements of immunoreactive inhibin have proven of little re levance in the diagnosis of testicular disorders. Dynamic evaluation o f the inhibin secretory reserve might detect a specific Sertoli cell d efect in a subgroup of infertile men. We compared the response of inhi bin and steroids to an intravenous injection of pure FSH (Metrodin, Se rono, 300 IU) in 13 infertile men with unilateral cryptorchidism to th at in eight normal fertile men. Blood was aspirated before, 24, 48, an d 72 h after the FSH injection. Two subgroups of patients with unilate ral cryptorchidism were detected: those who responded by secreting inh ibin in a pattern similar to normal men (seven patients), and those wh o responded poorly or not at all (six patients). The presumed cause of this difference is a defect of Sertoli cell reserve function due to a combination of insults to the testes, and not to cryptorchidism itsel f. The difference in response to FSH cannot be predicted from semen an alysis nor from static hormone measurements. Overall, inhibin levels c orrelated significantly with the serum concentrations of FSH (r=-0.36, P<0.05), testosterone (r=0.37, P<0.05), and 17-hydroxyprogesterone (r =0.66, P<0.001). It is concluded that, in infertile men with unilatera l cryptorchidism, stimulation of Sertoli cells by FSH can identify a s ubgroup of patients with Sertoli cell malfunction involving inhibin sy nthesis.