An estrogen test measures the level of the most important estrogen hormones ( estradiol, estriol, and estrone) in a blood or urine sample.

• Estradiol is the most commonly measured type of estrogen for nonpregnant women. The amount of estradiol in a woman's blood varies throughout her menstrual cycle. After menopause, estradiol production drops to a very low but constant level.
• Estriol levels usually are only measured during pregnancy. Estriol is produced in large amounts by the placenta, the tissue that links the fetus to the mother. It can be detected as early as the 9th week of pregnancy, and its levels increase until delivery. Estriol can also be measured in urine.
• Estrone may be measured in women who have gone through menopause to determine their estrogen levels. It also may be measured in men or women who might have cancer of the ovaries, testicles, or adrenal glands.

Both men and women produce estrogen hormones. Estrogens are responsible for female sexual development and function, such as breast development and the menstrual cycle. In women, estrogens are produced mainly in the ovaries and in the placenta during pregnancy. Small amounts are also produced by the adrenal glands. In men, small amounts of estrogens are produced by the adrenal glands and testicles. Small amounts of estrone are made throughout the body in most tissues, especially fat and muscle. This is the major source of estrogen in women who have gone through menopause.

Why It Is Done

A test for estrogen is done to:

• Help detect fetal birth defects (especially Down syndrome) during pregnancy. When the test for estriol is combined with alpha-fetoprotein (AFP) and human chorionic gonadotropin (hCG), it is called a triple screen test. When the amount of a hormone called inhibin A is also measured along with estriol, AFP, and hCG, the test is called a quad marker screen. Other blood tests and fetal ultrasound may be done as well.
• Evaluate estrogen-producing tumors of the ovaries in girls before menstruation starts and in women after menopause.
• Explain abnormal sexual characteristics in men, such as enlarged breasts (gynecomastia). This test can also help detect the presence of estrogen-producing tumors growing in the testicles.
• Monitor therapy with fertility medicines.

How To Prepare

No special preparation is required before having an estrogen test.

Tell your health professional if you:

• Are menstruating. Note where you are in your menstrual cycle.
• Are using birth control pills, patches, or rings and other forms of hormonal birth control.
• Are or might be pregnant.

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