How to prepare
No fasting is required. Eat and drink normally beforehand.
For women, cycle timing is important. FSH is most informative when collected on day 2 or 3 of your menstrual cycle (day 1 being the first day of full flow). This early-follicular measurement reflects baseline pituitary drive and provides the most meaningful assessment of ovarian reserve. Collection at other times in the cycle can produce different results that are harder to interpret.
If you are not menstruating, post-menopausal, or testing for another reason, timing is less critical. Your practitioner will advise.
After the test
Share your results with your GP, gynaecologist, endocrinologist, or fertility specialist. FSH is rarely interpreted in isolation — your practitioner will consider it alongside LH, oestradiol, AMH, and your clinical history.
For women with an elevated early-cycle FSH, a referral to a fertility specialist is a common next step. For men with elevated FSH, semen analysis and further assessment are typically recommended.
Your test results will be available in your private dashboard. If there are any urgent issues, we'll let you know so you can follow up with your health professional.
Understanding results
Results are reported in International Units per litre (IU/L). Reference ranges are specific to sex, age, and for women, cycle phase. Your result report will include the applicable range.
In women, an elevated early-cycle FSH (above the laboratory's reference for the follicular phase) can indicate reduced ovarian reserve or premature ovarian insufficiency. After menopause, FSH rises to persistently elevated levels. Very low FSH may point to a hypothalamic or pituitary issue.
In men, elevated FSH is associated with impaired spermatogenesis within the testes. Low FSH alongside low testosterone and low LH suggests a pituitary or hypothalamic cause.
FSH is most useful when interpreted alongside LH, oestradiol, and in fertility contexts, AMH.
