Follicle-Stimulating Hormone (FSH) Levels Test

Why this test may be ordered

• To help find the cause of infertility in women and men
• To check for medical conditions that affect how the ovaries work
• To find the reason for irregular or stopped menstrual periods in women of childbearing age
• To find out when a woman is most likely to get pregnant
• To find out if menopause or perimenopause may have begun (usually around age 50 for menopause, around age 45 for perimenopause; testing may be needed if symptoms are unclear or if premature menopause before age 40 or early menopause before age 45 is suspected). In women age 45 or older, testing is usually not needed because high FSH is a normal sign of perimenopause/menopause, but may be done for medical reasons such as premature menopause, early menopause, or unclear symptoms. Also if a woman has less interest in sex than usual. In men, to find the reason for a low sperm count, loss of muscle and/or body hair, or less interest in sex than usual. In women and men, to help diagnose disorders of the pituitary gland or hypothalamus (which may cause fatigue, weakness, decreased appetite and/or weight loss). In children and teens, to find out if a medical disorder is causing early puberty (signs before age 8 in girls or age 9 in boys) or delayed puberty (no signs by age 13 in girls or age 14 in boys).

Preparation and collection

Women who have menstrual periods may need to be tested at a specific time during their menstrual cycle. That's because FSH levels change throughout the month.

A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

Understanding results

To understand the results of your FSH test, your provider will consider your sex, age, symptoms, medical history, and the results of other hormone tests, especially your level of luteinizing hormone (LH).

• Higher levels of FSH: Higher levels of FSH are often a sign of a condition in the reproductive glands (ovaries or testicles) that prevents them from making normal levels of sex hormones. Limitation: High FSH may also be a sign of a condition outside of the reproductive glands that affects how the glands work. Next step: Your provider can explain what the results of your FSH test mean.
• Lower than normal levels of FSH: Lower than normal levels of FSH in women and men are often a sign of a problem with the pituitary gland or hypothalamus. Limitation: In women, low FSH levels may also be linked to rapid weight loss, being very underweight, or extreme exercise. Next step: To understand the results of your FSH test, your provider will consider your sex, age, symptoms, medical history, and the results of other hormone tests, especially your level of luteinizing hormone (LH).
• Child with early sexual development: high FSH and LH: High levels of FSH and LH mean the child has early puberty, also called precocious puberty. Limitation: In most cases, the cause is unknown. Next step: Your provider can explain what the results of your FSH test mean.
• Child with early sexual development: normal FSH and LH: Normal levels of FSH and LH mean the child has a type of early puberty called peripheral precocious puberty. This often means that a disorder in the testicles, ovaries, or adrenal glands is causing higher than normal levels of estrogen or testosterone. Limitation: Severe hypothyroidism and exposure to medicines that contain sex hormones may also cause this type of early puberty. Next step: To understand the results of your FSH test, your provider will consider your sex, age, symptoms, medical history, and the results of other hormone tests, especially your level of luteinizing hormone (LH).

• Results must be interpreted by a healthcare professional considering your sex, age, symptoms, medical history, and the results of other hormone tests, especially your level of luteinizing hormone (LH).
• At-home urine test kits can only find higher than normal FSH levels and should not be used to check whether you can become pregnant because they cannot accurately tell whether your ovaries are making eggs. If you use a home FSH test, discuss your symptoms and test results with your provider.

What to do next

Your provider can explain what the results of your FSH test mean. If you use a home FSH test, discuss your symptoms and test results with your provider.

• Why is this test being ordered for me or my child?
• What do my FSH results mean in my specific situation?
• Do I need any other tests?
• What follow-up is needed based on these results?

Evidence source

Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.

U.S. National Library of Medicine: Follicle-Stimulating Hormone (FSH) Levels Test

More lab tests A–Z

• Fetal Alcohol Spectrum Disorders (FASD) Screening
• Flu (Influenza) Test
• Fluoroscopy
• Food Allergy Testing
• Free Light Chains
• Fungal Culture Test