Compensated Hypospermatogenesis: Elevated Follicle-stimulating Hormone Predicts Decline in Semen Parameters Among Men With Normal Index Semen Analysis

Objective: To determine whether men with elevated follicle-stimulating hormone (FSH) and normal semen analysis (SA) are more likely to experience a decline in semen parameters over time compared to men with normal FSH. Methods: Men presenting for fertility evaluation between 2002 and 2020 with normal initial SA were dichotomized according to baseline FSH as normal (<7.6 IU/mL) vs elevated (≥7.6 IU/mL). Primary outcomes included the development of abnormal sperm concentration (<15 million/mL) and total motile sperm count <9 million. Secondary outcomes included abnormal sperm motility (<40%), morphology (<4%), and total number of SA abnormalities. Results: The final sample consisted of 858 men; 776 had normal FSH, and 82 had elevated FSH at presentation. Compared to men with normal FSH, men with elevated FSH had lower total motile sperm count (64.1 vs 107.3, P <.001) and higher testosterone levels (339 ng/dL vs 309 ng/dL, P =.03). At each follow-up timepoint, more men with elevated FSH had oligospermia compared to men with normal FSH. Men with elevated FSH were more likely to experience a decline in total motile sperm count below the intrauterine insemination threshold of 9 million and more likely to develop SA abnormalities over time. Conclusion: In men presenting for fertility evaluation with normal index SA, elevated FSH was associated with subsequent decline in semen parameters over time. Men with elevated FSH and normal SA, a condition we have termed compensated hypospermatogenesis, represent an at-risk population for whom close follow-up is warranted.