Inhibin B in the assessment of seminiferous tubular function.

Inhibin B is a testicular hormone that regulates follicle-stimulating hormone secretion in a negative feedback loop. In males, the serum level of inhibin B is detectable throughout life, with a prominent change in the first year of life and during puberty, reflecting the testicular response to the activity of the hypothalamic-pituitary-gonadal hormone axis. During childhood, the basal serum inhibin B level is a direct marker of the presence and function of testicular tissue that has proved useful in the diagnosis of patients with cryptorchidism or ambiguous genitalia. In adult men, the inhibin B level is closely related to spermatogenesis. Measurements of serum inhibin B may provide valuable clues for the differential diagnosis of male infertility. A further exploration of the relationship between inhibin B, Sertoli cell function and spermatogenesis will improve the usefulness of inhibin B as a tool in the investigation of male reproductive health.