Follicle stimulating hormone
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.
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:
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 FSH levels will differ, depending on a person's age and gender.
- Before puberty: 0 to 5.0 mIU/ml
- During puberty: 0.3 to 10.0 mIU/ml
- Adult: 1.5 to 12.4 mIU/ml
- Before puberty: 0 to 4.0 mIU/ml
- During puberty: 0.3 to 10.0 mIU/ml
- Women who are still menstruating: 4.7 to 21.5 mIU/ml
- After menopause: 25.8 to 134.8 mIU/ml
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
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 abuse, 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.
Veins and arteries vary in size from one person to another and from one side of the body to the other. Obtaining a blood sample 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
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
Borawski D, Bluth MH. Reproductive function and pregnancy. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 25.
Carmina E, Stanczyk FZ, Lobo RA. Laboratory assessment. In: Strauss JF, Barbieri RL, eds. Yen and Jaffe's Reproductive Endocrinology. 7th ed. Philadelphia, PA: Elsevier Saunders; 2014:chap 34.
Gruber HA, Farag AF. Evaluation of endocrine function. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 24.