What is a follicle-stimulating hormone (FSH) levels test?
This test measures the level of follicle-stimulating hormone (FSH) in your blood. FSH is made by your pituitary gland, a small gland located underneath the brain. FSH plays an important role in sexual development and functioning.
- In women, FSH helps control the menstrual cycle and stimulates the growth of eggs in the ovaries. FSH levels in women change throughout the menstrual cycle, with the highest levels happening just before an egg is released by the ovary. This is known as ovulation.
- In men, FSH helps control the production of sperm. Normally, FSH levels in men do not change very much.
- In children, FSH levels are usually low until puberty, when levels begin to rise. In girls, it helps signal the ovaries to make estrogen. In boys, it helps signal the testes to make testosterone.
Too much or too little FSH can cause a variety of problems, including infertility (the inability to get pregnant), menstrual difficulties in women, low sex drive in men, and early or delayed puberty in children.
Other names: follitropin, FSH, follicle-stimulating hormone: serum
What is it used for?
FSH works closely with another hormone called luteinizing hormone to control sexual functions. So a luteinizing hormone test is often done along with an FSH test. These tests are used in different ways, depending on whether you are a woman, man, or child.
In women, these tests are most often used to:
- Help find the cause of infertility
- Find out if there is a problem with ovarian function
- Find the reason for irregular or stopped menstrual periods
- Confirm the start of menopause, or perimenopause. Menopause is the time in a woman's life when her menstrual periods have stopped and she can't become pregnant anymore. It usually starts when a woman is around 50 years old. Perimenopause is the transition period before menopause. It can last for several years. FSH testing may be done towards the end of this transition.
In men, these tests are most often used to:
- Help find the cause of infertility
- Find the reason for a low sperm count
- Find out if there is a problem with the testicles
In children, these tests are most often used to help diagnose early or delayed puberty.
- Puberty is considered early if it starts before age 9 in girls and before age 10 in boys.
- Puberty is considered delayed if it hasn't started by age 13 in girls and by age 14 in boys.
Why do I need an FSH levels test?
If you are a woman, you may need this test if:
- You've been unable to get pregnant after 12 months of trying.
- Your menstrual cycle is irregular.
- Your periods have stopped. The test may be used to find out if you have gone through menopause or are in perimenopause
If you are a man, you may need this test if:
- You've been unable to get your partner pregnant after 12 months of trying.
- Your sex drive is decreased.
Both men and women may need testing if they have symptoms of a pituitary disorder. These include some of the symptoms listed above, as well as:
- Fatigue
- Weakness
- Weight loss
- Decreased appetite
Your child may need an FSH test if he or she does not seem to be starting puberty at the right age (either too early or too late).
What happens during an FSH levels test?
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.
Will I need to do anything to prepare for the test?
If you are a woman who has not gone through menopause, your provider may want to schedule your test at a specific time during your menstrual cycle.
Are there any risks to the test?
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.
