Test Overview

A follicle-stimulating hormone test measures the amount of follicle-stimulating hormone (FSH) in a blood sample. FSH is produced by the pituitary gland.

• 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 amounts of FSH and other hormones (luteinizing hormone, estrogen, and progesterone) are measured in both a man and a woman to determine why the couple can't become pregnant (infertility). The FSH level can help determine whether male or female sex organs (testicles or ovaries) are functioning properly.

Why It Is Done

A follicle-stimulating hormone (FSH) test may be done to:

• Help find the cause of infertility. FSH testing is commonly used to help evaluate a:
  • Woman's egg supply (ovarian reserve).
  • Man's low sperm count.
• Help evaluate menstrual problems, such as irregular or absent menstrual periods (amenorrhea). This can help determine whether the woman has gone through menopause.
• Determine if a child is going through early puberty (also called precocious puberty). Puberty is early when it starts in girls younger than age 9 and in boys younger than age 10.
• Determine why sexual features or organs are not developing when they should (delayed puberty).
• Help diagnose certain pituitary gland disorders, 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 having a follicle-stimulating hormone (FSH) test. Make sure your doctor has a complete list of all the prescription and over-the-counter medicines you are taking, including herbs and natural substances.

Tell your doctor if you have had a test that used a radioactive substance (tracer) within the last 7 days. Recent tests using a radioactive tracer (such as a thyroid scan or bone scan) can interfere with FSH test results.

Let your doctor know the first day of your last menstrual period. If your bleeding pattern is light or begins with spotting, the first day is the day of heaviest bleeding.

Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).

How It Is Done

The health professional drawing your blood will:

• Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
• Clean the needle site with alcohol.
• Put the needle into the vein. More than one needle stick may be needed.
• Attach a tube to the needle to fill it with blood.
• Remove the band from your arm when enough blood is collected.
• Apply a gauze pad or cotton ball over the needle site as the needle is removed.
• Apply pressure to the site and then a bandage.

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 It Feels

You may feel nothing at all from the needle puncture, or you may feel a brief sting or pinch as the needle goes through the skin. Some people feel a stinging pain while the needle is in the vein. But many people do not feel any pain or have only minor discomfort once the needle is positioned in the vein.

Risks

There is very little risk of complications from having blood drawn from a vein.

• You may develop a small bruise at the puncture site. You can reduce the risk of bruising by keeping pressure on the site for several minutes after the needle is withdrawn.
• In rare cases, the vein may become inflamed after the blood sample is taken. This condition is called phlebitis and is usually treated with a warm compress applied several times daily.
• Continued bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and other blood-thinning medicines can also make bleeding more likely. If you have bleeding or clotting problems, or if you take blood-thinning medicine, tell your doctor before your blood is drawn.

Results

A follicle-stimulating hormone test measures the amount of follicle-stimulating hormone (FSH) in a blood sample. The test results depend on your age and stage of sexual development.

The phase of a woman's menstrual cycle can affect results, so it is important to know the first day of your last menstrual period at the time the test is performed.

Results are usually available within 24 hours.

Normal

The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.

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 values

High FSH values in a woman may mean:

• Loss of ovarian function before age 40 (ovarian failure).
• Menopause has occurred.

High FSH values in a man may mean:

• Klinefelter syndrome.
• Testicles are absent or not functioning properly.
• Testicles have been damaged by a disease, such as alcohol dependence, or by treatments, such as X-rays or chemotherapy.

High values in children may mean that puberty is about to start.

Low values

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 functioning properly.
• A tumor is present that interferes with the brain's ability to control FSH production.
• Stress.
• Starvation or being very underweight.

What Affects the Test

Results of the follicle-stimulating hormone (FSH) test may be affected by:

• The use of hormones, such as testosterone, estrogen, and progesterone (including birth control pills).
• Heavy cigarette smoking.
• Age.
• The use of medicines, such as cimetidine, clomiphene, digitalis, and levodopa. Make sure your doctor has a complete list of all the prescription and over-the-counter medicines you are taking, including herbs and natural substances.
• Having a test such as a thyroid scan or bone scan that uses a radioactive substance within 1 week of the FSH test.

What To Think About

• If you are taking a medicine that contains testosterone, estrogen, or progesterone (such as birth control pills), ask your doctor whether you should stop taking it for several days before having a follicle-stimulating hormone (FSH) test.

References

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