Follicle-stimulating hormone: regulates ovarian follicles and testicular Sertoli cells.
What it is
FSH in IU/L. In women, levels vary across the cycle and rise after menopause. Cycle-day reporting is often required.
Follicle-stimulating hormone from the pituitary supports ovarian follicle growth and testicular Sertoli cell function. Reported in IU/L. In women, early follicular samples are often requested; postmenopausal FSH is typically high.
Why it matters
Used in fertility work-ups, menopause assessment, and male infertility pathways. Timing is everything, a random FSH in a cycling woman is hard to interpret.
This guide is educational only and cannot diagnose you. Discuss results, especially anything outside your laboratory’s reference interval, or that does not match how you feel, with a GP or other appropriately qualified clinician.
FSH helps assess ovarian reserve contexts, menopause, amenorrhoea, and male infertility: always with clinical history. Hormonal contraception suppresses the axis and invalidates many interpretations. A random mid-cycle FSH in a woman with irregular periods is easy to misread.
This guide is educational only and cannot diagnose you. Discuss results, especially anything outside your laboratory’s reference interval, or that does not match how you feel, with a GP or other appropriately qualified clinician.
How it affects the body
FSH from the pituitary supports gamete development. Feedback from inhibin and sex steroids closes the loop.
FSH drives gamete development; feedback from inhibin and sex steroids tunes pituitary output. Primary gonadal failure raises FSH; hypothalamic suppression lowers it.
For athletes
Amenorrhoeic athletes need a proper endocrine panel (not FSH alone) and relative energy deficiency evaluation with specialists who understand sport.
Female athletes with amenorrhoea need FSH as part of a wider panel (oestradiol, LH, prolactin, TSH, pregnancy test as appropriate) plus energy-availability assessment, not FSH in isolation.
For fertility planning when you want AMH with key reproductive and thyroid markers in one private panel. AMH does not predict natural conception chances.
