- In women, FSH helps control the menstrual cycle and the production of eggs by the ovaries. The amount of FSH varies throughout a woman's menstrual cycle and is highest just before she releases an egg (ovulates).
- In men, FSH helps control the production of sperm. The amount of FSH in men normally remains constant.
The FSH level can help find out if male or female sex organs (testicles or ovaries) are working as they should.
Why It Is Done
The amounts of FSH and other hormones are measured to:
- Find out why a couple can't become pregnant.
- Help diagnose menstrual problems or find out whether a woman has gone through menopause.
- See why a child is going through early or delayed puberty.
- Help diagnose certain pituitary gland problems, such as a tumor.
How To Prepare
Many medicines, such as cimetidine, clomiphene, digitalis, and levodopa, can change your test results. You may be asked to stop taking medicines (including birth control pills) that contain estrogen or progesterone or both for up to 4 weeks before you have a follicle-stimulating hormone (FSH) test. Make sure your doctor has a complete list of all the prescription and over-the-counter medicines you take, including herbs and natural substances.
How It Is Done
A health professional uses a needle to take a blood sample, usually from an arm.
For a woman who is having problems with her menstrual cycle or who cannot become pregnant, more than one blood sample may be needed to help identify a follicle-stimulating hormone (FSH) problem. A sample may be taken each day for several days in a row.
How long the test takes
The test will take a few minutes.
How It Feels
When a blood sample is taken, you may feel nothing at all from the needle. Or you might feel a quick sting or pinch.
There is very little chance of having a problem from this test. When a blood sample is taken, a small bruise may form at the site.
Each lab has a different range for what's normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn't in the normal range may still be normal for you.
Many conditions can change FSH levels. Your doctor will discuss any significant abnormal results with you in relation to your symptoms and past health.
High FSH values in a woman may mean:
- A genetic disease is present.
- Loss of ovarian function before age 40 (premature ovarian failure).
- Low egg supply (ovarian reserve).
- Menopause has occurred.
High FSH values in a man may mean:
- Klinefelter syndrome.
- Testicles are absent or not working as they should.
- Testicles have been damaged by a disease or by treatments, such as X-rays or chemotherapy.
High values in children may mean that puberty is about to start.
Low FSH values may mean:
- A woman is not producing eggs (prevents ovulation) or a man is not producing sperm.
- An area of the brain (the hypothalamus or pituitary gland) is not working as it should.
- A tumor is present that interferes with the brain's ability to control FSH production.
- Starvation or being very underweight.
- A female athlete is not having menstrual cycles.
Current as of: August 2, 2022
Author: Healthwise Staff
Sarah Marshall MD - Family Medicine
Martin J. Gabica MD - Family Medicine
E. Gregory Thompson MD - Internal Medicine
Kathleen Romito MD - Family Medicine