FSH

Overview & Description

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

Who is a candidate for the test?

Fertility in men and women, as well as menstruation in women, are regulated by a complex interaction of hormones. The ovaries, pituitary gland, and hypothalamus produce these hormones. Follicle-stimulating hormone, or FSH, causes the follicles within the ovaries to mature.

FSH levels may be measured if the healthcare provider suspects a problem with:

  • menopause, a time in life when menstruation stops
  • ovarian cysts, which are fluid-filled sacs on the ovary
  • precocious puberty, or puberty that happens at an abnormally young age
  • delayed puberty, or puberty that hasn't occurred by the time it should
  • female infertility, or inability to become pregnant
  • male infertility, or the inability to impregnate a woman
  • anovulatory bleeding, which is abnormal vaginal bleeding not related to a regular menstruation cycle
  • amenorrhea, or the absence of menstruation
  • testes that are absent or abnormally small

    • How is the test performed?

    A blood sample is taken from a vein on the forearm or hand. First, the skin over the vein is cleaned with an antiseptic. Next, a strong rubber tube, or "tourniquet," is wrapped around the upper arm. This enlarges the veins in the lower arm by restricting blood flow through them. A fine needle is gently inserted into a vein, and the tourniquet is removed. Blood flows from the vein through the needle, and is collected in a syringe or vial. After the needle is withdrawn, the puncture site is covered for a short time to prevent bleeding. The blood sample is sent to the laboratory to determine the amount of FSH circulating in the blood.

    Preparation & Expectations

    What is involved in preparation for the test?

    There is generally no preparation for this test. However, the healthcare provider may want to have the test done during a particular time of a woman's menstrual cycle.

    Results and Values

    What do the test results mean?

    Normal values depend upon the sex of the person and other factors. Greater than normal levels of FSH may be found in the following conditions:

  • polycystic ovary disease, a condition that causes ovarian cysts and menstrual cycle problems or irregularities
  • menopause
  • premature ovarian failure, which may be genetic or related to radiation exposure
  • Klinefelter syndrome, a genetic disorder that causes testicular failure
  • Turner syndrome, a genetic disorder in which the ovaries fail to respond to pituitary hormones
  • absence of the testes
  • precocious puberty

    • Lower than normal levels may be seen with:

  • a poorly functioning hypothalamus
  • some cases of infertility
  • anorexia nervosa, an eating disorder
  • exercise-induced amenorrhea, a condition in which a woman stops menstruating after she over-exercises
  • bulimia nervosa, an eating disorder with overeating followed by induced vomiting
  • use of oral contraceptive pills or other medications
  • breastfeeding

    • Attribution

    Author:Eva Martin, MD
    Date Written:
    Editor:Smith, Mary Ellen, BS
    Edit Date:03/19/00
    Reviewer:Joan McNicholl, PharmD
    Date Reviewed:09/20/01