[Inhibin B as a marker of spermatogenesis. A new dimension in andrology]

In 1932, McCullagh postulated the existence of a specific hormone of the testis, regulating FSH secretion. He named this hormone inhibin. As we know today, several proteins of the inhibin family are produced in the Sertoli cells. The major product is inhibin B, consisting of a alpha- and a beta-subunit. It is also present in spermatogonia, spermatocytes and early spermatids. The serum levels of inhibin B increase in puberty. In the adult man they are correlated positively to sperm count and testis volume, but negatively to FSH levels. These correlations exist also in OAT syndrome independent of the cause of spermatogenic failure. In azoospermia high serum levels of inhibin B predict the existence of spermatozoa in the testis. This improves the prediction of the success of a TESE. It may be that the determination of inhibin B is superior to that of FSH.