OBJECTIVETo evaluate the predictive value of serum inhibin B (INH B) levels as an indicator of the presence of testicular spermatozoa in nonobstructive azoospermia.

METHODSForty patients with nonobstructive azoospermia (NOA), 20 patients with obstructive azoospermia (OA), and 10 fertile volunteers were involved in this study. A chemoluminescence method was used to measure the levels of FSH; Inhibin B was analysed by using sandwich enzyme-linked immuno-sorbent assay.

RESULTSPatients with nonobstructive azoospermia has significantly higher levels of serum FSH [(21.34 +/- 12.15) IU/L] and significantly lower levels of inhibin B [(53.15 +/- 58.74) ng/L] than patients with obstructive azoospermia [FSH: (3.94 +/- 1.52) IU/L, INH B: (162.49 +/- 78.38) ng/L, P < 0.01] and fertile volunteers [FSH: (4.27 +/- 2.84) IU/L, INH B: (228.49 +/- 110.68) ng/L, P < 0.01]. Mean serum inhibin B were significantly higher in patients with nonobstructive azoospermia who had spermatozoa on TESE than in those in whom no spermatozoa was found on TESE [INHB: (90.31 +/- 72.18) ng/L vs (19.54 +/- 20.38) ng/L, r = 0.528, P < 0.01], but mean FSH levels did not have similar predictive power (P > 0.05).

CONCLUSIONSerum INH B level seems to be more accurate than serum FSH in the prediction of presence of testicular spermatozoa in patients with nonobstructive azoospermia. Serum inhibin B determination may be substitute of TESE as a diagnostic index.