Estrogens

Also known as: Estrogen fractions/fractionated; Estrone (E1); Estradiol (E2); Estriol (E3); (over 20 different forms of estrogen have been described)

Formal name: Estrogens

The Test Sample

What is being tested?

Estrogens are a group of steroids that regulate the menstrual cycle and function as the main female sex hormones. The most common forms of estrogens tested are estrone (E1), estradiol (estradiol-17 beta, E2), and estriol (E3). Total estrogens are most commonly measured in blood or urine.

Estrogens are responsible for the development of female sex organs and secondary sex characteristics and are tied to the menstrual cycle and pregnancy. They are considered the main sex hormones in women and are present in small quantities in men. E1 and E2 are the two main estrogens in non-pregnant females, while E3 is the main pregnancy hormone.

Estrone (E1) is derived from metabolites from the adrenal gland and is often made in adipose tissue (fat). Estrone can be converted into estrdiol or estriol when needed. Estrone is present in small amounts in children prior to puberty and then increases slightly at puberty for both males and females. While levels remain constant in adult males, it will increase and fluctuate for females during the menstrual cycle. After menopause, it becomes the major estrogen, with E2 and E3 levels diminishing greatly.
Estradiol (E2) is the predominant form and is produced primarily in the ovaries with additional amounts produced by the adrenal glands in women and in the testes and adrenal glands in men. In menstruating women, levels vary throughout the month, rising and falling in concert with FSH (follicle-stimulating hormone), LH (luteinizing hormone), and progesterone as follicles are stimulated in the ovaries, an egg is released, and the uterus prepares for a potential pregnancy. The level is lowest at the beginning of the menstrual cycle and rise to their highest level just before the release of an egg from the ovary (ovulation). Normal levels of estradiol provide for proper ovulation, fertilization of the egg (conception), and pregnancy, in addition to promoting healthy bone structure and regulating cholesterol levels.
Estriol (E3) is the major estrogen in pregnancy, with relatively large amounts produced by the developing placenta. Estriol levels start to rise in the eighth week of pregnancy and continue to rise until shortly before delivery. Estriol circulating in maternal blood is quickly cleared out of the body. Each measurement of estriol is a snapshot of what is happening with the placenta and fetus, but there is also natural daily variation in estriol concentrations.

How is the sample collected for testing?

A blood sample is drawn from a vein in your arm or a 24-hour urine sample is collected. Depending on the test requested, your doctor may have you collect a fresh saliva sample in a plastic tube; however, saliva testing is less common.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed, but the timing of the sample will be correlated with your menstrual cycle or, when you are pregnant, to the gestational age.