Follicle-Stimulating Hormone (FSH) Levels Test

What is a follicle-stimulating hormone (FSH) levels test?

This test measures the level of follicle-stimulating hormone (FSH) in a sample of your blood. A hormone is a chemical messenger in your bloodstream that controls the actions of certain cells or organs. FSH plays an important role in sexual development in children and fertility in adults.

• In women who menstruate (have periods), FSH helps control the menstrual cycle. It triggers the growth of eggs in the ovaries and gets the eggs ready for ovulation. Ovulation is when an ovary releases an egg so it can travel down a fallopian tube where it can be fertilized by sperm.
• In men, FSH helps control the amount of sperm that the testicles (testes) make. It also affects how healthy the sperm are.
• In children, FSH levels are normally low until puberty starts. Then FSH levels begin to rise along with the levels of other hormones. The increase in all these hormones triggers the physical changes of puberty:
  • In girls, FSH tells the ovaries to start making the hormone estrogen. Estrogen is involved in the growth of breasts, body hair, and menstruation.
  • In boys, FSH tells the testicles to start making the hormone testosterone. Testosterone is involved in the growth of facial and body hair, changes in a boy's voice, and sperm production.

FSH levels are controlled by a complex system of hormones made in different parts of your body. Abnormal levels of FSH may be a sign of a problem with any of these parts. They include your:

• Pituitary gland, a small gland at the base of your brain. It makes FSH.
• Hypothalamus, a part of your brain. It makes hormones that tell your pituitary gland how much FSH to make.
• Reproductive glands, your ovaries or testicles. The amount of sex hormones they make let your hypothalamus and pituitary gland know when to start and stop making FSH.

Other names: follitropin, FSH, follicle-stimulating hormone: serum, pituitary gonadotropins

What is it used for?

FSH testing is used to help diagnose conditions that cause too much or too little FSH. The specific way the test is used depends on your sex and age.

In women, an FSH test may be used to:

• Help find the cause of infertility
• Check for medical conditions that affect how the ovaries work
• Find the reason for irregular or stopped menstrual periods in women of childbearing age
• Find out when a woman is most likely to get pregnant
• Find out if menopause or perimenopause may have begun:
  • Menopause happens when the ovaries stop making certain hormones, and menstrual periods have stopped for 12 months in a row. This usually happens around age 50.
  • Perimenopause is the time leading up to menopause when hormones and periods begin to change. It usually starts around age 45.

In men, an FSH test may be used to:

• Help find the cause of infertility
• Find the reason for a low sperm count
• Check for medical conditions that affect the testicles

In women and men, FSH testing may be used to help diagnose disorders of the:

• Pituitary gland
• Hypothalamus

In children and teens, FSH testing is most often used to find out if a medical disorder is causing early or delayed (late) puberty.

An FSH test is often used with a blood test for another hormone made in the pituitary gland called luteinizing hormone (LH). These two hormones work together to control sexual development and reproduction. Blood tests to check estrogen, testosterone, and progesterone levels are also commonly used with FSH testing.

Why do I need an FSH levels test?

For women:
You may need this test if:

• You've been unable to get pregnant after 12 months of trying.
• Your menstrual periods aren't regular or have stopped.
  If you're age 45 or older, testing usually isn't needed. That's because high levels of FSH are a normal sign of perimenopause and menopause. As your ovaries release fewer eggs, your body makes more hormones to try to trigger ovulation. But you may need an FSH test along with other hormone tests if there is a medical reason, including:
  • Premature menopause (age 40 or younger)
  • Early menopause (before age 45)
  • Having symptoms that may be related to menopause, but the cause isn't clear
• You have a less interest in sex than usual.

For men:
You may need this test if:

• You've been unable to get your partner pregnant after 12 months of trying.
• You have less interest in sex than usual.
• You have a low sperm count.
• You have a loss of muscle and/or body hair.

For women and men:
You may need an FSH test if your health care provider thinks you could have a pituitary disorder. Pituitary problems can affect fertility and decrease your interest in sex. They may also cause symptoms, such as:

• Fatigue
• Weakness
• Decreased appetite and/or weight loss

Children and teens may need FSH testing if puberty seems to be starting too early or too late:

• Early puberty means showing signs of sexual development before age 8 in girls and age 9 in boys.
• Delayed puberty means not showing signs of sexual development by age 13 in girls and age 14 in boys.

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?

Women who have menstrual periods may need to be tested at a specific time during their menstrual cycle. That's because FSH levels change throughout the month.

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.

What do the results mean?

To understand the results of your FSH test, your provider will consider your sex, age, symptoms, medical history, and the results of other hormone tests, especially your level of luteinizing hormone (LH). Your provider can explain what the results of your FSH test mean.

Generally, in women and men:

• Higher levels of FSH are often a sign of a condition in the reproductive glands (ovaries or testicles) that prevents them from making normal levels of sex hormones. The pituitary responds by making more FSH to try to get them to work properly. High FSH may also be a sign of a condition outside of the reproductive glands that affects how the glands work.

  Conditions linked to high FSH levels include:

  • In women:
    • Ovaries that never developed normally
    • Primary ovarian insufficiency (POI)
    • Polycystic ovary syndrome (PCOS)
    • Menopause or perimenopause
    • An ovarian tumor
    • Thyroid diseases or adrenal gland disorders
    • A chromosomal disorder, such as Turner syndrome
  • In men:
    • A germ cell tumor (a tumor that starts in the cells that become sperm)
    • Mumps
    • A physical injury to the testicles
    • A chromosomal disorder, such as Klinefelter syndrome
  • In women and men, damage to the ovaries or testicles, which may be caused by:
    • Autoimmune disease

    • Radiation therapy and/or chemotherapy

• Lower than normal levels of FSH in women and men are often a sign of a problem with the pituitary gland or hypothalamus. These problems may make it hard for your body to make FSH and LH.
  
  

  In women, low FSH levels may also be linked to rapid weight loss, being very underweight, or extreme exercise.

Generally, in children with signs of early sexual development (before age 8 in girls or age 9 in boys):

• High levels of FSH and LH mean the child has early puberty, also called precocious puberty. In most cases, the cause is unknown. But in certain cases, the cause is a problem in the brain, such as:
  • A brain tumor
  • A past brain injury
  • A past brain infection, such as meningitis or encephalitis
• Normal levels of FSH and LH mean the child has a type of early puberty called peripheral precocious puberty. This often means that a disorder in the testicles, ovaries, or adrenal glands is causing higher than normal levels of estrogen or testosterone. Severe hypothyroidism and exposure to medicines that contain sex hormones may also cause this type of early puberty.

Generally, in teens with no signs of sexual development by age 13 for girls or age 14 for boys, low or normal levels of FSH and LH usually mean delayed puberty. Many teens with delayed puberty are healthy and go through normal puberty at a later age. But delayed puberty may be caused by certain medical conditions, such as:

• Poor nutrition from a long-term illness or eating disorder
• Hypogonadism, which is when the ovaries or testicles make little or no hormone. It may be caused by:
  • Certain genetic disorders, including Kallmann syndrome
  • Tumors in the brain or pituitary gland
  • Turner syndrome in girls
  • Klinefelter syndrome in boys
  • Certain autoimmune disorders
  • Radiation therapy or chemotherapy

If you have questions about test results, talk with your or your child's provider.

Learn more about laboratory tests, reference ranges, and understanding results.

Is there anything else I need to know about an FSH levels test?

At-home test kits that measure FSH levels in urine (pee) may help women find out if menopause or perimenopause is causing symptoms, such as irregular periods, vaginal dryness, or hot flashes.

Home tests can only find higher than normal FSH levels. They shouldn't be used to check whether you can become pregnant because they can't accurately tell whether your ovaries are making eggs. If you use a home FSH test, discuss your symptoms and test results with your provider.