Serum inhibin B may be a reliable marker of the presence of testicular spermatozoa in patients with nonobstructive azoospermia.

Objective: To establish the predictive value of serum inhibin B levels as an indicator of the presence of testicular spermatozoa in nonobstructive azoospermia, compared with the traditional serum FSH marker.
Design: Prospective study.
Setting: Private high-complexity reproductive center with university affiliation.
Patient(s): Seventy-eight patients with nonobstructive azoospermia, 15 patients with obstructive azoospermia, and 10 fertile volunteers.
Intervention(s): Blood samples, testicular sperm extraction, percutaneous epididymal sperm aspiration, and semen collection.
Main Outcome Measure(s): Serum levels of inhibin B and FSH and presence of spermatozoa on TESE, PESA, or regular semen analysis.
Result(s): Patients with nonobstructive azoospermia has significantly higher levels of serum FSH and significantly lower levels of inhibin B. Mean inhibin B serum levels were significantly higher in patients with nonobstructive azoospermia who had spermatozoa on TESE than in those in whom no spermatozoa were found (89.31 +/- 73.24 pg/mL vs. 19.23 +/- 22.34 pg/mL), but mean FSH serum levels did not have similar predictive power (21.37 +/- 12.92 IU/mL vs. 19.27 +/- 10.28 IU/mL). The cut-off level of inhibin B separating both groups, as determined by the receiver-operating characteristic curves, was >53 pg/mL.
Conclusion(s): Serum inhibin B level seems to be more accurate than serum FSH level in prediction of the presence of testicular spermatozoa in patients with nonobstructive azoospermia.