Finasteride-induced secondary infertility associated with sperm DNA damage.

Objective: To report a case of low-dose finasteride-induced secondary infertility with associated elevated sperm DNA fragmentation index (DFI) and otherwise normal semen parameters.

Design: Case report.

Setting: University hospital.

Patient(s): A 48-year-old man on low-dose finasteride and his 37-year-old wife with normal menses and normal gynecologic exam.

Intervention(s): Determination of sperm DFI and discontinuation of low-dose finasteride.

Main Outcome Measure(s): Sperm DFI.

Result(s): The sperm DFI done a year earlier was 30%. This value was unchanged when repeated 2 months later. The patient was advised to stop finasteride. Three months after discontinuing the finasteride, the DFI decreased to 21% and subsequent DFI after another 3 months improved to 16.5%. To date, there is still no documented full-term pregnancy or live birth.

Conclusion(s): The significant reduction in DFI within 3 months of finasteride cessation and continued improvement suggests a causal link between finasteride and sperm DNA damage. We hypothesize that low-dose finasteride may exert a negative influence on sperm DNA integrity, resulting in increased pregnancy losses. We suggest that in infertile men using finasteride, sperm DFI should be measured in addition to semen parameters, and a trial of discontinuation of finasteride may be warranted.