Utility of inhibin B in the management of male infertility]

Inhibin B (INHB) is an hormone produced by Sertoli's cells that exercises a negative feedback on FSH secretion. In this study we analyze its diagnostic value as a marker of spermatogenesis and its prognostic value for testicular sperm extraction in azoospermic patients.Between June 2003 and April 2007 we studied 504 infertile males in our Fertility Department. Until May 2006 we determined INHB only in patients with a sperm count <10M/ml. Since then INHB was determined in every patient due to the present study. 158 determinations were finally performed using enzymoimmunoassay considering normal values between 80 and 300pg/ml. We correlated INHB values with other hormones, spermatic count and, in case of azoospermia (24 patients), with success/failure of surgical sperm retrieval from testes (TESE) to use for intracytoplasmatic sperm injection (ICSI).A significant correlation was observed between INHB and FSH (r=-0.469, p<0.001) and LH (r=-0.399, p<0.001) but not with testosterone, prolactin, estradiol and SHBG. Sperm count was better correlated with INHB (r=0.247; p<0.003) than with FSH (r: -0.157; p<0.052). INHB and FSH were altered in 57.6% and 42.1% of azoospermia respectively, 42.1% and 11.1% in severe oligospermia (0-2M/ml) and 5% and 3.3% in oligospermia (>2M/ml) and normozoospermia. In azoospemic patients PPV for success in testicular sperm extraction was 81.8 % for normal INHB and 76.6% for normal FSH. NPV for failure of sperm retrieval was 61.6% for low INHB and 63.6% for high FSH.An inverse correlation exists between INHB and FSH and LH levels. INHB correlates better than FSH with sperm count. In azoospermia and oligospermia (<2M/ml), low INHB is more sensitive to detect testicular damage than high FSH. Normal INHB level predicts better than FSH the success of testicular sperm extraction for ICSI, although the favourable outcome can never be assured.