(798) Finasteride 1 mg: Silent Impacts on Male Fertility Despite Preserved Hormonal Balance

Introduction Finasteride, a type-2 5α-reductase inhibitor, is prescribed for benign prostatic hyperplasia and androgenetic alopecia. Effects on male fertility remains uncertain. Objective This study aimed to assess the impact of finasteride 1 mg/day on semen parameters, hormonal profiles, sexual function, and psychological status in men of reproductive age. Methods This retrospective, cross-sectional case-control study was approved by the Institutional Review Board (No. 92540525.0.0000.0068) and included 465 men aged 18–60 years (69 finasteride users and 396 controls). Semen analyses followed WHO 2021 criteria. Hormones measured included total and free testosterone (TT, FT), follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), sex hormone-binding globulin (SHBG), prolactin (PRL), cortisol, and dihydrotestosterone (DHT). Metabolic (glucose, HbA1c, lipids, 25-hydroxyvitamin D) and thyroid parameters were also assessed. Sexual and psychological status were evaluated using the International Index of Erectile Function (IIEF-15), quantitative Androgen Deficiency in the Aging Male (qADAM), Male Sexual Quotient (MSQ), Beck Depression and Anxiety Inventories (BDI, BAI), Hamilton Anxiety Scale (HAM-A), and Montgomery–Åsberg Depression Rating Scale (MADRS). Univariate comparisons and multivariate linear regression were adjusted for covariates. Statistical significance was set at p < 0.05. Results Mean age 41.9 ± 8.4 years; BMI 27.1 ± 3.9 kg/m2. Finasteride users had similar metabolic and hormonal profiles, except for higher HDL cholesterol (49.7 ± 8.7 vs. 46.1 ± 10.6 mg/dL; p = 0.025). Mean duration of finasteride treatment was 73.5 ± 72.0 months. Semen quality was reduced in finasteride users: sperm concentration 55.6 ± 58.3 vs. 90.6 ± 93.8 ×106/mL, total sperm count 151.9 ± 205.1 vs. 254.1 ± 258.9 ×106/ejaculate, and total motile sperm count 72.6 ± 79.8 vs. 166.6 ± 182.9 ×106 (all p < 0.001). Sperm morphology Kruger (2.0 ± 2.7 vs. 3.9 ± 4.0%) and WHO criteria (9.0 ± 8.2 vs. 14.9 ± 9.7%). Multivariate regression confirmed finasteride as an independent predictor of lower sperm concentration (β = −26.9; p = 0.025), total sperm count (β = −72.9; p = 0.031), total motile sperm count (β = −75.7; p = 0.002), and sperm morphology (β = −4.18; p = 0.002). DHT was lower (0.17 ± 0.20 vs. 0.58 ± 0.49 ng/mL; p < 0.001), but TT, FT, FSH, LH, and E2 were similar between groups. Questionnaire analyses showed mild, nonsignificant declines in erectile function and vitality. Sexual satisfaction, mood, urinary, and stress scores were comparable. Conclusions Finasteride 1 mg/day reduces significantly sperm production and morphology without affecting endocrine, sexual, or psychological function. Disclosure No