What is FSH and what does it measure?
FSH drives ovarian follicle development in women and spermatogenesis in men. Persistent FSH >25 mIU/mL with absent menses for 12 months supports menopause diagnosis.
Full answer
Follicle-stimulating hormone (FSH) is a pituitary gonadotropin that drives ovarian follicle development in women and Sertoli cell function (spermatogenesis) in men. FSH defines reproductive stage in women (perimenopause, menopause) and characterizes male hypogonadism as primary (testicular failure, elevated FSH) or secondary (pituitary, low/normal FSH). oMeds provider review pairs FSH with LH, estradiol, and (in men) total testosterone. Persistent FSH >25 mIU/mL with absent menses for 12 months supports menopause diagnosis. In men with low testosterone and elevated FSH, the primary lesion is testicular; with low FSH, the lesion is pituitary.
Educational. Not a substitute for individualized provider review.
- FSH — Primary source · oMeds
- Reviewed by Dr. Laura Purdy, MD, MBA · Clinical Director, oMeds · Last reviewed 2026-05-29