Definition

The follicle stimulating hormone (FSH) blood test measures the level of FSH in blood. FSH is a hormone released by the pituitary gland, located on the underside of the brain.

Alternative Names

Follicle stimulating hormone; Menopause - FSH; Vaginal bleeding - FSH

How the Test is Performed

A blood sample is needed.

How to Prepare for the Test

If you are a woman of childbearing age, your health care provider may want you to have the test done on certain days of your menstrual cycle.

How the Test will Feel

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.

Why the Test is Performed

In women, FSH helps manage the menstrual cycle and stimulates the ovaries to produce eggs. The test is used to help diagnose or evaluate:

• Menopause
• Women who have polycystic ovary syndrome, ovarian cysts
• Abnormal vaginal or menstrual bleeding
• Problems becoming pregnant, or infertility

In men, FSH stimulates production of sperm. The test is used to help diagnose or evaluate:

• Problems becoming pregnant, or infertility
• Men who do not have testicles or whose testicles are underdeveloped

In children, FSH is involved with the development of sexual features. The test is ordered for children:

• Who develop sexual features at a very young age
• Who are delayed in starting puberty

Normal Results

Normal FSH levels will differ, depending on a person's age and sex.

Male:

• Before puberty: 0 to 5.0 mIU/mL (0 to 5.0 IU/L)
• During puberty: 0.3 to 10.0 mIU/mL (0.3 to 10.0 IU/L)
• Adult: 1.5 to 12.4 mIU/mL (1.5 to 12.4 IU/L)

Female:

• Before puberty: 0 to 4.0 mIU/mL (0 to 4.0 IU/L)
• During puberty: 0.3 to 10.0 mIU/mL (0.3 to 10.0 IU/L)
• Women who are still menstruating: 4.7 to 21.5 mIU/mL (4.5 to 21.5 IU/L)
• After menopause: 25.8 to 134.8 mIU/mL (25.8 to 134.8 IU/L)

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test result.

What Abnormal Results Mean

High FSH levels in women may be present:

• During or after menopause, including premature menopause
• When receiving hormone therapy
• Due to certain types of tumor in the pituitary gland
• Due to Turner syndrome

Low FSH levels in women may be present due to:

• Being very underweight or having had recent rapid weight loss
• Not producing eggs (not ovulating)
• Parts of the brain (the pituitary gland or hypothalamus) not producing normal amounts of some or all of its hormones
• Pregnancy

High FSH levels in men may mean the testicles are not functioning correctly due to:

• Advancing age (male menopause)
• Damage to testicles caused by alcohol overuse, chemotherapy, or radiation
• Problems with genes, such as Klinefelter syndrome
• Treatment with hormones
• Certain tumors in the pituitary gland

Low FSH levels in men may mean parts of the brain (the pituitary gland or hypothalamus) do not produce normal amounts of some or all of its hormones.

High FSH levels in boys or girls may mean that puberty is about to start.

Risks

There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight, but may include:

• Excessive bleeding
• Fainting or feeling lightheaded
• Multiple punctures to locate veins
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

References

Garibaldi LR, Chemaitilly W. Disorders of pubertal development. In: Kliegman RM, St Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 578.

Jeelani R, Bluth MH. Reproductive function and pregnancy. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 26.

Lobo RA. Infertility: etiology, diagnostic evaluation, management, prognosis. In: Gershenson DM, Lentz GM, Valea FA, Lobo RA, eds. Comprehensive Gynecology. 8th ed. Philadelphia, PA: Elsevier; 2022:chap 40.