Follicle-stimulating hormone (FSH) is a pituitary hormone that triggers follicle growth and maturation in ovaries and supports spermatogenesis in testes. In women FSH stimulates ovarian follicle development and granulosa cells to produce estrogen; in men it acts on Sertoli cells to promote sperm production and inhibin B secretion. Its release is controlled by GnRH and feedback from sex steroids and inhibin.

FSH (follicle‑stimulating hormone) varies with menstrual cycle and age. Typical reference ranges: follicular phase about 3.5–12.5 mIU/mL, mid‑cycle peak about 4.7–21.5 mIU/mL, luteal phase about 1.7–7.7 mIU/mL. Postmenopausal levels are much higher, often 25–135 mIU/mL. Interpret results with your clinician, as lab ranges and context differ; abnormal values may need follow‑up.

Low FSH can cause menstrual disturbances (irregular or absent periods, anovulation) and infertility in women, plus symptoms from low estrogen such as vaginal dryness, hot flashes and increased fracture risk. In men it often causes reduced sperm production, smaller testes and fertility problems, sometimes with low libido. Chronic low FSH may lead to low energy and decreased secondary sexual characteristics.

High FSH usually signals primary gonadal failure: in women it indicates diminished ovarian reserve, premature ovarian insufficiency or menopause (causing irregular periods, hot flashes and low estrogen); in men it points to testicular failure with low testosterone and reduced sperm production. High FSH often correlates with infertility and requires further medical evaluation and hormone testing to identify cause and guide treatment.

Stress can disrupt the hypothalamic–pituitary–gonadal axis and sometimes alter gonadotropin release, causing transient changes in FSH and menstrual function. However, persistently high FSH is typically due to ovarian aging or primary ovarian insufficiency rather than everyday stress. If FSH remains elevated on repeat testing, seek medical evaluation to determine the underlying cause and appropriate management.

Costs vary by country and provider. In the UK an FSH blood test is typically free through the NHS; in India it commonly ranges ₹200–₹1,200 at private labs. In the US out‑of‑pocket prices commonly run about $30–$200 depending on the lab, location and whether it’s part of a panel or covered by insurance. Ask your clinic or lab for exact fees.