Do 5α-Reductase Inhibitors Raise Circulating Serum Testosterone Levels? A Comprehensive Review and Meta-Analysis Explaining Paradoxical Results

The document analyzed the impact of 5α-reductase inhibitors (5α-RIs), specifically finasteride and dutasteride, on serum testosterone (T) levels through a review and meta-analysis of 11 studies involving 1,784 patients. The results indicated that there was no significant increase in serum T levels after treatment with 5α-RIs, with a mean baseline change of 27 (95% confidence interval 1–54). The increase in T levels was not consistent across all studies, and no significant changes were observed in luteinizing hormone, follicle-stimulating hormone, sex hormone-binding globulin (SHBG), or estradiol values. The review concluded that 5α-RI therapy does not consistently raise serum T levels, and any observed increases are likely due to changes in SHBG binding rather than an increase in T biosynthesis.