FSH blood test: what it measures and what your result means

Medically reviewed by Dr Lebeth Jacob · 21 October 2026

Quick answer: FSH (follicle-stimulating hormone) is made by the pituitary gland in your brain. In women it helps eggs develop each month; in men it helps produce sperm. FSH is often tested to look into fertility, irregular periods or the menopause. Because it changes through the menstrual cycle and in the years around the menopause, one result is always read alongside your age, cycle and symptoms.

What is FSH?

FSH is a signal from the pituitary gland to the ovaries or testicles. In women, it tells the ovaries to grow follicles, each containing an egg. In men, it tells the testicles to make sperm.

When the ovaries or testicles respond less well, the pituitary sends more FSH to push them harder. That's why FSH goes up as women approach the menopause.

Why is FSH tested?

  • You've been trying for a baby without success
  • Your periods are irregular or have stopped
  • You're under 45 and have symptoms that could be the menopause, such as hot flushes or night sweats
  • You have symptoms of PCOS
  • In men, as part of fertility tests or to look into low testosterone

What does a high FSH result mean?

In women, a high FSH usually means the ovaries are responding less, as happens around the menopause. Common reasons are:

  • Perimenopause or menopause
  • The ovaries stopping working before 40 (premature ovarian insufficiency)
  • Past chemotherapy, radiotherapy or ovarian surgery

In men, a high FSH can mean the testicles aren't making sperm as well as usual. This can follow an injury, a past infection such as mumps, or cancer treatment, or be caused by an inherited condition.

What does a low FSH result mean?

A low FSH can mean the pituitary gland isn't sending a strong signal. Common reasons are:

  • Hormonal contraception or HRT
  • Pregnancy
  • Very low body weight, or a lot of intense exercise
  • Stress or serious illness
  • In men, using anabolic steroids or testosterone
  • Rarely, a problem with the pituitary gland

In PCOS, FSH is often normal while another hormone, LH, is raised.

What can affect your result?

  • Timing: if you have periods, FSH is usually tested on day 2 to 5 of your cycle (day 1 is the first day of bleeding), unless your doctor says otherwise
  • Hormonal contraception and HRT change FSH, so results may not be reliable while you're taking them
  • FSH can go up and down a lot in the years before the menopause

When to see a GP

Your results report shows the laboratory's range and flags any result outside it. Speak to your GP if:

  • Your periods have stopped or become very irregular and you're under 45 (under 40, see them promptly)
  • You've been trying to get pregnant for a year, or for six months if you're 36 or over
  • Your FSH is flagged high or low and you're not sure why
  • You're a man with a flagged FSH, or concerns about fertility

How we test FSH

You can have FSH tested with a blood sample taken at one of our 250+ partner clinics, or with a finger-prick kit at home. Samples are analysed by a UKAS-accredited laboratory. Results are usually ready in 3–5 working days, with a doctor's comments on every result.

Tests that include FSH

Prices for in-clinic tests include your appointment. Compare every test with FSH in the biomarker explorer

Frequently asked questions

What FSH level indicates menopause?

A raised FSH alongside menopausal symptoms suggests perimenopause or menopause. But FSH can rise and fall from month to month at that stage, so one result can't confirm or rule it out. In women over 45 with typical symptoms, a GP can usually diagnose the menopause without a blood test.

What is a normal FSH level to get pregnant?

There's no FSH level that guarantees or rules out pregnancy. A raised FSH can mean fewer eggs are left, but many women with a raised level still conceive. Doctors often look at AMH as well, which gives a better picture of egg reserve.

When should I have an FSH test?

If you have periods, usually on day 2 to 5 of your cycle. If your periods have stopped or are very irregular, you can test on any day.

Can I test FSH while on the pill?

The combined pill and some other hormonal contraception lower FSH, so the result may not reflect your natural level. Ask your doctor whether it's worth testing while you're taking it.

What does FSH do in men?

It tells the testicles to make sperm. A high FSH in men can point to a problem with sperm production.