FSH Blood Test

What is the FSH blood test?

The FSH test measures the level of follicle stimulating hormone (FSH) in your blood. This hormone is produced by a gland in your brain. In women FSH stimulates the production of eggs and is important in the regulation of menstruation. In men FSH stimulates the production of sperm.

Why is this test done?

The FSH test is usually done to help diagnose problems with sexual development, menstruation, and fertility. The test is used to help diagnose:

• menopause
• women who have polycystic ovary disease, ovarian cysts, irregular vaginal bleeding, or infertility
• children who start sexual development at a very young age
• men who have infertility
• men who do not have testicles or whose testicles are underdeveloped.

How do I prepare for this test?

• You may need to avoid taking certain medicines before the test because they might affect the test result. Make sure your healthcare provider knows about any medicines, herbs, or supplements that you are taking. Don't stop any of your regular medicines without first consulting with your healthcare provider.

How is the test done?

A small amount of blood is taken from your arm with a needle. The blood is collected in tubes and sent to a lab.

Having this test will take just a few minutes of your time. There is no risk of getting AIDS, hepatitis, or any other blood-borne disease from this test.

How will I get the test result?

Ask your healthcare provider when and how you will get the result of your test.

What does the test result mean?

The normal range of FSH depends on your age and sex.

• For women who are menstruating, the normal range is 5 mIU/mL to 30 mIU/mL
• For women in menopause or after menopause, the values range from 50 mIU/mL to 100 mIU/mL.
• For men the levels range from 5 to 20 mIU/mL.

Other hormone tests are done with the FSH test. The results of the different tests are interpreted together to make a diagnosis.

In women FSH and the blood level of the hormone estradiol are measured. (Estradiol is a type of estrogen. Estrogens are hormones responsible for the growth and functioning of a woman's reproductive tract.)

• The level of FSH is increased and the level of estradiol is decreased in women who are in menopause or who have gone through menopause.
• FSH and estradiol levels are higher than normal if a woman has ovarian cancer or adrenal cancer.
• Hormone therapy can cause increased levels of FSH and estradiol.
• Both the FSH and estradiol levels are higher than normal in girls who have started puberty at a very young age.
• FSH and estradiol levels are lower than normal in women who have anorexia nervosa or whose hormone regulating system (the pituitary and hypothalamus) isn't working normally.
• FSH is higher than normal and estradiol is lower than normal if a woman has Turner's syndrome (a genetic abnormality).

In men, FSH is measured along with the blood level of the hormone testosterone.

• The FSH and testosterone levels are both lower than normal if a man's pituitary gland is not making enough hormones or if the hypothalamus (another part of the brain's hormone-regulating system) is not working normally.
• The FSH and testosterone levels are higher than normal if a man is being treated with hormones for a medical condition.
• FSH and testosterone levels are higher than normal in boys who have started puberty at a very young age.
• The FSH level is higher than normal and the testosterone level is lower than normal if a man has Klinefelter's syndrome (a genetic abnormality), if his testicles have been removed, and if he has gone through male menopause.

There are many other reasons why FSH test results may be outside the normal range. Sometimes the results vary with recent activity or diet. At other times the way the sample is collected or stored can influence the results. If you are concerned about your lab results, talk to your healthcare provider.

What if my test results are not normal?

Test results are only one part of a larger picture that takes into account your medical history and current health. Sometimes a test needs to be repeated to check the first result. Talk to your healthcare provider about your result and ask questions. Ask if and when you need more tests.