FSH (follicle-stimulating hormone)
Pituitary hormone that drives egg maturation and sperm production
Also known as
Definition
FSH (follitropin) is made in the pituitary gland. In women it stimulates the maturation of eggs in the ovaries and helps regulate the menstrual cycle; in men it drives sperm production in the testicles. Its release is controlled by the hypothalamus and by feedback from the sex hormones. FSH is usually measured together with LH and estradiol, progesterone or testosterone, for example for questions about the cycle, fertility, menopause or puberty.
| Parameter | Value |
|---|---|
| Unit | IU/l (equivalent to mIU/ml) |
| Reference Range | Men: 1.5–12.4 IU/l | Women with a menstrual cycle: 4.7–21.5 IU/l (varies with cycle phase) | Women after menopause: 25.8–134.8 IU/l. Labs differ; the reference range on your own report is what counts. Discuss deviations with your doctor. |
Agree on your personal target range with your doctor.
1 IU/l equals 1 mIU/ml; the numbers are identical in both units.
↓ What a low value means
Low FSH can be linked to a disorder of the pituitary gland or hypothalamus in both women and men. In women, being very underweight, rapid weight loss, very intense exercise, not ovulating or pregnancy are further possibilities. Without LH and sex hormones, a single FSH value is hard to interpret. Discuss deviations with your doctor.
↑ What a high value means
High FSH often shows that the ovaries or testicles produce few sex hormones and the pituitary is compensating. In women this is normal during perimenopause and menopause, but it can also be linked to primary ovarian insufficiency, polycystic ovary syndrome (PCOS) or Turner syndrome. In men, damage to the testicles, for example from injury, mumps, alcohol, chemotherapy or radiation, or Klinefelter syndrome are possibilities. Hormone treatment can also raise FSH. Your doctor interprets the result.
When to test
In women with a menstrual cycle, FSH is often measured on a specific cycle day because the level changes over the month; your practice sets the day. Typical reasons are not conceiving after 12 months of trying, irregular or absent periods, questions about early menopause and, in men, a low sperm count. From age 45, the test is usually not needed to assess menopause.
Frequently asked questions
How are FSH and LH related? +
Both hormones come from the pituitary gland and work together to control sexual development and reproduction. That is why they are usually measured together. To interpret FSH, your doctor mainly looks at LH, age, sex and symptoms.
Does FSH show menopause? +
High FSH is normal in perimenopause and menopause because the ovaries make fewer hormones. From age 45, an FSH test is usually not needed for this. With premature menopause at 40 or younger, early menopause before 45 or unclear symptoms, it can be useful together with other hormone values. Your doctor interprets the result.
What can at-home FSH urine tests do? +
They only detect elevated FSH and can give hints as to whether symptoms such as irregular periods or hot flashes are related to menopause. They cannot tell whether pregnancy is possible. Discuss results and symptoms with your doctor.
What role does FSH play in men? +
FSH stimulates sperm production in the testicles and affects sperm quality. It is measured, for example, when a couple cannot conceive, with a low sperm count or when a disorder of the testicles or pituitary gland is suspected.
FSH (follicle-stimulating hormone)
Sources
Last updated: October 05, 2026
This information is for orientation only and does not replace medical advice. Reference ranges can vary by laboratory, method and country.