An estrogen test measures the level of the most
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
- 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
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.
For pregnant women, the level of estriol in the blood is used in a
maternal serum triple or quadruple screening test.
Generally done between 15 and 20 weeks, these tests check the levels of three
or four substances in a pregnant woman's blood. The triple screen checks
alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), and a type of
estrogen (unconjugated estriol, or uE3). The quad screen checks these
substances and the level of the hormone inhibin A. The levels of these
substances—along with a woman's age and other factors—help the doctor estimate
the chance that the baby may have certain problems or birth defects.
- Pregnancy: Should I Have Screening Tests for Birth Defects?