Serum inhibin B in combination with serum follicle-stimulating hormone (FSH) is a more sensitive marker than serum FSH alone for impaired spermatogenesis in men, but cannot predict the presence of sperm in testicular tissue samples

The measurement of serum. FSH is useful in the diagnostic workup of the inf ertile male, but fails to predict the presence of sperm in testicular tissu e. We investigated whether inhibin B reflects testicular morphology and the presence of sperm more accurately than FSH. Serum inbibin B and gonadotrop in levels were determined in 91 infertile men undergoing diagnostic bilater al testicular biopsy. In 52 of the 91 patients multiple samples were taken for testicular sperm extraction (TESE). Inhibin B levels were (mean +/- SEM ) 238 +/- 32 pg/mL in men with normal spermatogenesis (n = 9), 102 +/- 18 p g/ml; in men with spermatogenetic arrest (n = 15), 98 +/- 16 pg/mL in hypos permatogenesis (n = 23), 41 +/- 6 pg/mL, in focal Sertoli cell-only syndrom e (SCO; n = 26), and 27 +/- 8 pg/mL in complete SCO (n = 18). The percentag e of SCO tubuli was more strongly correlated to serum inbibin B (r = -0.58; P < 0.01) than to FSH (r = 0.34; P < 0.05). Similarly, the percentage of t ubules with elongated spermatids was significantly (P < 0.05) more strongly correlated to serum inhibin B (r = 0.65; P < 0.01) than to FSH (r = -0.4; P < 0.01). Thus, inhibin B is slightly more sensitive than FSH as an index of the spermatogenic status. Neither FSH nor inhibin B drone, however, coul d predict the type of spermatogenetic damage exactly. The combination of FS H and inhibin B had high diagnostic sensitivity (88%) and specificity (83%) for the presence of elongated spermatids in testicular biopsies. Sperm cou ld be retrieved in 34 (65%) of the TESE patients. The combination of inhibi n B and FSH measurement showed a sensitivity of 75% and a specificity of 73 % when identifying patients in whom sperm could possibly be retrieved by TE SE. We conclude that although the measurement of serum inhibin B improves t he sensitivity of predictive tests for the presence of sperm in histology o r for TESE, this parameter cannot accurately predict TESE outcome.