Follicle-Stimulating Hormone Test

Definition

The follicle-stimulating hormone (FSH) test measures the amount of FSH in the blood. FSH is a hormone that regulates the growth and development of eggs and sperm, and this test is used to diagnose or evaluate disorders involving the pituitary gland and reproductive system.

Purpose

FSH testing is performed if a physician suspects the patient may have a disorder involving the reproductive system or pituitary gland. The pituitary gland produces FSH, which stimulates the growth of the sacks (follicles) that surround the eggs in a woman's ovaries. This is important for the process of ovulation, in which the egg is released. In men, FSH stimulates production of sperm. If there are abnormal levels of FSH in the blood it may mean that one of several disorders are present. Normal fluctuations occur as a result of puberty, the menstrual cycle, pregnancy, and menopause.

The FSH test is performed more often on women than on men. In women, it is used to determine if menopause has begun, to diagnose infertility and menstrual disorders (such as anovulatory bleeding), to measure hormone levels in children who enter puberty at an early age, and to diagnose other disorders. In men, it can be used to determine early puberty, abnormal tissue growth on one or more of the hormone-secreting (endocrine) glands (called multiple endocrine neoplasia), or to diagnose other disorders.

Description

The FSH test is a blood test. Blood will be drawn from the patient and analyzed in a laboratory.

Preparation

In preparation for the test, there are no food or fluid intake restrictions. Patients may be advised to discontinue certain medications for 48 hours before the test. A menstruating woman having hot flashes or irregular periods should be tested on the second or third day of her menstrual cycle. A woman who has missed a period and is having other menopausal symptoms can be tested at any time.

Aftercare

No aftercare is necessary.

Risks

There are no risks associated with this test.

Normal results

Normal FSH test results vary according to age and sexual maturity. The phase of a woman's menstrual cycle or use of birth-control pills also affects test results.

For an adult male, normal results range from about 4-25 units of FSH in every liter of blood (U/L) or about 5-20 micro-international units in every milliliter.

For a premenopausal woman, normal values range from 4-30 U/L or 5-20 micro-international units per milliliter. In a pregnant woman, FSH levels are too low to measure. After menopause, normal values range from 40-250 U/L or 50-100 micro-international units per milliliter.

FSH levels fluctuate during premenopause. If no other symptoms are present, an elevated FSH level should not be interpreted as proof that menopause has begun.

Abnormal results

Anorexia nervosa and disorders of the hypothalamus or pituitary gland can result in abnormally low FSH levels.

Abnormal levels can also indicate:

• infertility
• hypopituitarism
• klinefelter syndrome (in men)
• turner syndrome
• ovarian failure
• polycystic ovary syndrome

Resources

OTHER

"Follicle-Stimulating Hormone Test." Health Answers.com February 25, 1998. 〈http://www.healthanswers.com〉.

KEY TERMS

Anovulatory bleeding— Bleeding without release of an egg from an ovary.

Hypopituitarism— Underactivity of the pituitary gland.

Hypothalamus— The part of the brain that controls the endocrine system.

Klinefelter's syndrome— Chromosomal abnormality characterized by small testes and male infertility.

Multiple endocrine neoplasia— Abnormal tissue growth on one or more of the endocrine (hormone-secreting) glands.

Polycystic ovary disease— A condition in which a woman has little or no menstruation, is infertile, has excessive body hair, and is obese. The ovaries may contain several cysts.

Turner syndrome— Chromosomal abnormality characterized by immature reproductive organs in women.