Testosterone-to-follicle stimulating hormone ratio predicts sperm retrieval success in men with idiopathic nonobstructive azoospermia

OBJECTIVE: To evaluate novel preoperative hormonal predictors of sperm retrieval success in men with idiopathic nonobstructive azoospermia (NOA) undergoing microsurgical testicular sperm extraction (mTESE). DESIGN: Multi-institutional retrospective cohort study conducted between 2014 and 2024. SUBJECTS: A total of 60 men with strictly defined idiopathic NOA from multiple sites participating in the MOBYUS Male Infertility Research Consortium were included, comprising a prediction cohort (n = 30) and an independent multi-institutional validation cohort (n = 30). Idiopathic NOA was defined by azoospermia on two separate semen analyses without prior paternity, evidence of obstruction, prior genitourinary surgery, documented genetic abnormalities, or use of empirical medical therapy within 1 year before surgery. Sensitivity analyses were performed by excluding men with follicle-stimulating hormone (FSH) levels 20 and LH