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

At a Glance

Why Get Tested?

To measure or monitor your estrogen levels if you are a woman who has unexplained abnormal menstrual cycles, abnormal or heavy bleeding, infertility, symptoms of menopause, or any other hormonal alterations; also used to test for fetal-placental status during early stages of pregnancy and to evaluate feminization, the presence of female-like characteristics in males

When to Get Tested?

When you show symptoms of a hormone imbalance, abnormal vaginal bleeding, unusual and/or early sex organ development (female), or when your doctor wants to monitor the health of your placenta and fetus during pregnancy; when a man shows signs of feminization

Sample Required?

A blood sample drawn from a vein in your arm, a 24-hour urine sample, or sometimes a fresh saliva sample

Test Preparation Needed?


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.

The Test

Common Questions

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Article Sources

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.

Sources Used in Current Review

Pagana, K. D. & Pagana, T. J. (© 2007). Mosby's Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 416-419.

Clarke, W. and Dufour, D. R., Editors (© 2006). Contemporary Practice in Clinical Chemistry: AACC Press, Washington, DC. Pp 359-360.

S3 Wu, A. (© 2006). Tietz Clinical Guide to Laboratory Tests, 4th Edition: Saunders Elsevier, St. Louis, MO. Pp 366-369, 374-377.

(Updated 2009 September 29). Hormones and Menopause. National Institute on Aging [On-line information]. Available online at through Accessed November 2009.

Brzyski, R. and Jensen, J. (Revised 2007 March). Female Reproductive Endocrinology, Introduction. Merck Manual for Healthcare Professionals [On-line information]. Available online at through Accessed November 2009.

Vorvick, L. and Storck, S. (Updated 2009 July 26). Estradiol test. MedlinePlus Medical Encyclopedia [On-line information]. Available online at Accessed November 2009.

Sources Used in Previous Reviews

ACOG. (October 2001, Number 31). ACOG Practice Bulletin, Clinical Management Guidelines for Obstetrician-Gynecologists, Assessment of Risk Factors for Preterm Birth. American College of Obstetricians and Gynecologists [Guideline from Obstet Gynecol 2001:98:709-716]. Available online through

MEDLINEplus (3 October 2001). Medical Encyclopedia: Estrogen Overdose. U.S. National Library of Medicine, Bethesda, MD. MEDLINEplus. Available online at

MEDLINEplus (9 August 2001). Medical Encyclopedia: Estradiol - Test. U.S. National Library of Medicine, Bethesda, MD. MEDLINEplus. Available online at

Thomas, Clayton L., Editor (1997). Taber's Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].

Pagana, Kathleen D. & Pagana, Timothy J. (1999). Mosby's Diagnostic and Laboratory Test Reference 4th Edition: Mosby, Inc., Saint Louis, MO.

Well-Connected Report: Menopause, Estrogen Loss and Their Treatments (March 2001). What Are Other Disorders Affected by Estrogen? WebMDHealth, [On-line serial]. Available online at through

ACOG (3 October 2001). Hormonal Contraception Studies Examine Easier Methods, Menstrual Regulation. American College of Obstetricians and Gynecologists [Press release]. Available online at through

ACOG (31 March 2001). ERT and Endometrial Cancer Survivors. American College of Obstetricians and Gynecologists [Press release]. Available online at through

AMWA (2000). Hormone Replacement Therapy and Breast Cancer Risk, Q & A. American Medical Women's Association [On-line serial]. Available online at through

Women's Health Information Center (June 2001). Efficacy of Estradiol for the Treatment of Depressive Disorders in Perimenopausal Women. The Journal of the American Medical Association [Abstract from Arch Gen Psychiatry. 2001;58:529-534]. Available online through

Moving Beyond Cancer (4 October 2001). Managing Menopausal Symptoms Hormonal transitions. [On-line medical information]. Available online at through

Drugs & Herbs (24 March 2000, Medically reviewed October 2001) Estradiol Tropical Patches. LycosHealth with WebMD [On-line Medical Information]. Available online at through

Association of Women for the Advancement of Research and Education Typical Hormone Products. Available online at through

ARUP's Guide To Clinical Laboratory Testing. Estriol, Serum and Urine. Available online at through

ARUP's Guide To Clinical Laboratory Testing. Maternal Serum Screening. Available online at through