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.