An FSH reference values table helps you read your blood result quickly. In the follicular phase (days 2-5 of your cycle) a normal FSH sits between roughly 3.5 and 12.5 IU/L. After menopause it is far higher: roughly 26 to 135 IU/L. The hormone swings sharply across the cycle. Your result can only be judged if you know which cycle day the blood was drawn.
FSH values per cycle phase (IU/L)
Follicular phase (days 2-5): 3.5-12.5. Mid-cycle peak: 4.7-21.5. Luteal phase: 1.7-7.7. Postmenopausal: 25.8-134.8. Reference ranges differ slightly per laboratory, so always compare against the range printed on your own result.
FSH values per life stage
Prepubertal: below 4 IU/L. Reproductive age: see the cycle values above. Perimenopause: highly variable, often above 10 IU/L on day 3 but normal again the following month. Postmenopause: 25.8-134.8 IU/L. During pregnancy: suppressed.
FSH values in men
In men the hormone has no cycle, so there is a single range: 1.5 to 12.4 IU/L. Those limits come from the same reference cohort as the female values above, measured in 319 men. If you are here because you are reading a partner's result: the hormone is the same, the job differs. In women it ripens the follicles, in men it drives sperm production.
A raised FSH in a man usually means the pituitary is pushing harder because the testes are responding less. The hormone itself is not the problem, it is the signal that more effort is needed. That pattern fits reduced sperm production and is almost always read alongside LH and testosterone. A high result with a high LH and a low testosterone points one way. The same result with a normal testosterone points another.
A low FSH in a man comes from above instead: the pituitary is sending too little signal. One cause is easily missed: testosterone from outside the body. That covers prescribed testosterone therapy and anabolic steroids alike. Both suppress FSH and LH together. The result then reads low without anything being wrong with the pituitary. Always mention it to your doctor, because without that information the result cannot be interpreted.
How to interpret your result
Measured on day 3: below 10 IU/L fits a normal ovarian reserve. 10-15 IU/L is borderline. Above 15 IU/L fits reduced ovarian function. Above 25 IU/L fits perimenopause. Above 40 IU/L with twelve months without a period fits menopause.
What does a low FSH value mean?
Almost all explanation of FSH concerns a value that is too high. The low end gets far less attention, yet it tells the opposite story. A high FSH comes from below: your ovaries respond less, so your pituitary pushes harder. A low FSH comes from above: the signal itself is lagging.
The most common explanation is also the simplest. Hormonal contraception suppresses FSH. Do you take the pill, or use a ring, patch or implant? Then a low result says nothing about your ovarian reserve. You are measuring the effect of the contraception rather than that of your ovaries. That is the first question to settle before investigating a low value further.
Other causes of a low result, usually alongside a low oestradiol:
- Too little available energy - substantial weight loss, a low body weight, or training hard without eating enough. The body then turns the cycle down for a while.
- Prolonged stress - through the same route in the brain.
- A raised prolactin - prolactin dampens the signal that drives FSH and LH, so both read low.
- A disorder of the pituitary itself - rare. It is the reason to always discuss a low value when periods stop.
A low value is therefore rarely a reason to worry about your ovarian reserve. It is a reason to find out why the signal is low, particularly if your periods have stopped.
Why a normal FSH does not rule out menopause
In women over 45, FSH is not recommended for diagnosing menopause. Dutch GP guidance (NHG-Standaard De overgang) makes that diagnosis on the pattern of symptoms and periods, not on a blood value. The hormone fluctuates most sharply during perimenopause. A single normal result does not rule menopause out, and a single raised result does not prove it.
That still leaves the question of how high FSH actually goes in menopause answerable. After menopause the reference range is 25.8 to 134.8 IU/L. That is roughly ten times the follicular-phase range. On a day 3 measurement, a value above 25 IU/L fits perimenopause. Above 40 IU/L, with twelve months without a period, fits menopause. The number does not make the diagnosis, but it does show which order of magnitude you are in.
When are abnormal values relevant?
Discuss an abnormal result with your GP or gynaecologist, who looks at the whole picture. To measure FSH alongside the other cycle hormones, the women's hormone test covers FSH, LH, oestradiol and progesterone in one draw. To measure FSH on its own, use the standalone FSH test.
Frequently asked questions
Which cycle day should FSH be measured on?
Days 2 to 5, counting from the first day of your period. Outside that window the reference ranges above do not apply. If you no longer menstruate, the day does not matter.
Is FSH the same as AMH?
No, they are different hormones providing complementary information. FSH rises as ovarian reserve decreases; AMH drops. AMH can also be measured on any cycle day, FSH cannot.
Do I need to fast for an FSH test?
No, fasting is not needed. The cycle day matters far more than whether you have eaten.
What is FSH on a blood test?
FSH stands for follicle-stimulating hormone and is made by your pituitary, a small gland at the base of the brain. On your lab form it appears as the abbreviation, with a result in IU/L. It is almost always measured together with LH and oestradiol. Those three only mean something alongside each other. Fasting is not required. The cycle day is: if you still menstruate, days 2 to 5 are the right window.
What does a high FSH mean?
A high FSH means your pituitary is pushing harder because your ovaries are responding less. On a day 3 measurement, 10 to 15 IU/L fits a declining ovarian reserve. Above 15 IU/L fits reduced ovarian function. Above 25 IU/L fits perimenopause. In men a high result points to reduced sperm production. A single raised result is never enough to establish anything. That is truest in perimenopause, when the hormone swings sharply month to month.
How high does FSH go in menopause?
After menopause the reference range is 25.8 to 134.8 IU/L. That is roughly ten times the follicular-phase range. In perimenopause a day 3 value above 25 IU/L fits. Above 40 IU/L, with twelve months without a period, fits menopause. Over the age of 45 the measurement is not recommended for diagnosing menopause. That is exactly when the hormone fluctuates most.
Which blood values point to menopause?
The combination of a high FSH and a low oestradiol fits menopause. That means a value above roughly 25 to 40 IU/L. The oestradiol sits below the premenopausal range. In practice no single blood value makes the diagnosis. Dutch GP guidance works from your symptom pattern and the course of your periods. Blood testing mainly adds something if you are younger than 45 and your periods have stopped.
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