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 infertile male, but fails to predict the presence of sperm in testicular tissue. We investigated whether inhibin B reflects testicular morphology and the presence of sperm more accurately than FSH. Serum inhibin B and gonadotropin levels were determined in 91 infertile men undergoing diagnostic bilateral 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 pg/mL in men with spermatogenetic arrest (n = 15), 98+/-16 pg/mL in hypospermatogenesis (n = 23), 41+/-6 pg/mL in focal Sertoli cell-only syndrome (SCO; n = 26), and 27+/-8 pg/mL in complete SCO (n = 18). The percentage of SCO tubuli was more strongly correlated to serum inhibin B (r = -0.58; P