Also Known As
Estrogen Fractions/fractionated
Estrone (E1)
Estradiol (E2)
Estriol (E3)
Estrogenic Hormones
This article was last reviewed on
This article waslast modified on July 2, 2020.
At a Glance
Why Get Tested?

To measure or monitor your estrogen levels; to detect an abnormal level or hormone imbalance as a cause of your signs and symptoms; to monitor treatment for infertility or symptoms of menopause; sometimes to test for fetal-placental status during early stages of pregnancy

When To Get Tested?

Women: when you show symptoms of a hormone imbalance, such as abnormal vaginal bleeding, lack of menstrual periods, unusual and/or early or late sex organ development; when you are undergoing infertility treatment or therapy for menopause symptoms; when you are pregnant and your healthcare practitioner wants to monitor the health of your placenta and developing baby, if it is a high-risk pregnancy

Men: when you have signs of feminization, such as enlarged breasts (gynecomastia)

Sample Required?

A blood sample drawn from a vein or a 24-hour urine sample

Test Preparation Needed?

None, but the timing of a woman's sample will be correlated with her menstrual cycle or, if pregnant, with the gestational age of the baby.

You may be able to find your test results on your laboratory's website or patient portal. However, you are currently at Lab Tests Online. You may have been directed here by your lab's website in order to provide you with background information about the test(s) you had performed. You will need to return to your lab's website or portal, or contact your healthcare practitioner in order to obtain your test results.

Lab Tests Online is an award-winning patient education website offering information on laboratory tests. The content on the site, which has been reviewed by laboratory scientists and other medical professionals, provides general explanations of what results might mean for each test listed on the site, such as what a high or low value might suggest to your healthcare practitioner about your health or medical condition.

The reference ranges for your tests can be found on your laboratory report. They are typically found to the right of your results.

If you do not have your lab report, consult your healthcare provider or the laboratory that performed the test(s) to obtain the reference range.

Laboratory test results are not meaningful by themselves. Their meaning comes from comparison to reference ranges. Reference ranges are the values expected for a healthy person. They are sometimes called "normal" values. By comparing your test results with reference values, you and your healthcare provider can see if any of your test results fall outside the range of expected values. Values that are outside expected ranges can provide clues to help identify possible conditions or diseases.

While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability can occur due to differences in testing equipment, chemical reagents, and techniques. This is a reason why so few reference ranges are provided on this site. It is important to know that you must use the range supplied by the laboratory that performed your test to evaluate whether your results are "within normal limits."

For more information, please read the article Reference Ranges and What They Mean.

What is being tested?

Estrogens are a group of steroids that are responsible for the development and function of reproductive organs and the formation of secondary sex characteristics in women. Along with another hormone, progesterone, they help regulate the menstrual cycle, are involved in the growth of breasts and the uterus, and help maintain a healthy pregnancy. Though considered the main sex hormones for women, they are also found in men and play a role in bone metabolism and growth in both sexes. Estrogen tests measure one of three components: estrone (E1), estradiol (E2), or estriol (E3) in the blood or urine.

  • Estrone (E1) is directly converted from androstenedione (from the adrenal gland) or indirectly from other androgens. E1 can also be produced by the ovaries and placenta, testicles, and adipose (fat) tissues. E2 and E1 can be converted into each other as needed. E1 is the primary estrogen in men and in post-menopausal women.
  • Estradiol (E2) is primarily produced in the ovaries under stimulation of FSH and LH in pre-menopausal women and in the testicles in men. E2 is converted from E1 in post-menopausal women. It is the most potent estrogen and the one that is present in the highest concentration in non-pregnant, pre-menopausal women. E2 levels vary depending on a woman's age and reproductive status. They are a good marker of ovarian function.
  • Estriol (E3) is produced by the placenta, with concentrations rising throughout a woman's pregnancy. Increasing levels are an indication of the health of the pregnancy and developing baby. Estriol is part of the second trimester maternal serum screen, a test performed to evaluate fetal risk due to certain chromosomal abnormalities. Very low levels of E3 are present in non-pregnant women or men.

Estrogen in Girls and Women
The types and amounts of estrogen normally present in a woman's blood will vary throughout her lifetime. Levels vary during each menstrual cycle, during pregnancy, and on a daily basis.

At Birth
Estradiol (E2) and estrone (E1) are high but fall within a few days. Concentration levels are minimal during early childhood.

At Puberty
Concentrations of E2 and E1 begin to rise as puberty approaches. These estrogens are responsible for the development of breasts, uterine growth, and (with other hormones) the onset and regulation of menstruation. A moderate amount of E1 is present from puberty to menopause. This concentration will vary during the day but is otherwise relatively stable.

During Menstruation
The menstrual cycle is approximately 28 days long and consists of two phases, follicular phase (day 1-14) and luteal phase (day 15-28). During each cycle, estradiol (E2) and several other hormones normally rise and then fall in a specific sequence.

During Pregnancy
Estriol (E3) is the primary estrogen present during pregnancy. It is produced by the placenta, starts to rise in the eighth week of pregnancy, and continues to rise throughout the pregnancy. A sharp increase of E3 occurs approximately 4 weeks prior to the onset of labor. 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.

E1 also rises during pregnancy, increasing as much as 10-fold between weeks 24 and 40. After delivery, E1 falls and E3 again becomes essentially undetectable.

During Menopause
Estrone (E1) is the primary estrogen present during menopause. E2 concentrations significantly decrease as ovarian production wanes and eventually stabilize at a low level.

Estrogen in Boys and Men
The types and amounts of estrogen normally present in a man's blood change, but they vary much less over time than a woman's and they are much lower.

Accordion Title
Common Questions
  • How is it used?

    Estrogen tests are used to detect a deficiency or excess in a woman and to help diagnose a variety of conditions associated with this imbalance. They may also be used to help determine the timing of a woman's ovulation and may be ordered to monitor the health status of the developing baby and placenta during pregnancy. In a man, estrogen testing may be performed to detect a hormone excess and its cause.

    Estrogen tests measure one of three components: estrone (E1), estradiol (E2), or estriol (E3). These tests each have different uses.

    In Girls and Women

    Estradiol (E2) and/or estrone (E1) testing may be ordered to:

    • Help diagnose early-onset puberty, when a young girl develops secondary sex characteristics sooner than expected; or delayed puberty, when a girl shows delayed development of secondary sex characteristics or start of menstruation
    • Investigate menstrual abnormalities, such as lack of menstrual periods (amenorrhea), infertility, and abnormal vaginal bleeding
    • Evaluate the function of the ovaries and detect ovarian failure
    • Monitor follicle development in the ovary in the days prior to in vitro fertilization by making serial measurements of estradiol
    • Monitor hormone replacement therapy that is given to assist fertility
    • Monitor menopausal hormone replacement therapy that is given to alleviate symptoms associated with estrogen deficiency
    • Detect estrogen-producing tumors
    • Monitor anti-estrogen therapy, as in breast cancer

    Estriol (E3) testing:

    In Boys and Men

    Estradiol (E2) and/or estrone (E1) testing in boys or men may be ordered to:

    • Help diagnose delayed puberty
    • Help diagnose the cause of enlarged breasts (gynecomastia) or other signs of feminization
    • Detect a relative estrogen excess that is due to a testosterone or androgen deficiency
    • Detect estrogen-producing tumors
  • When is it ordered?

    In Girls and Women

    Estradiol (E2) and/or estrone (E1) testing in girls and women may be ordered when:

    • A girl's sex organs develop earlier or later than normally expected
    • A woman has symptoms such as abnormal vaginal bleeding after menopause or abnormal or lack of menstrual cycles
    • A woman is experiencing infertility; a series of estradiol measurements over the course of a woman's menstrual cycle may be done to monitor follicle development prior to in vitro fertilization techniques (timed with a surge in estradiol).
    • A woman is having symptoms of menopause, including hot flashes, night sweats, insomnia, and/or irregular or lack of menstrual periods
    • A menopausal woman is taking hormone replacement therapy; her health practitioner may periodically order estrone levels to monitor treatment.

    Estriol (E3) testing in women may be ordered:

    • During pregnancy, a healthcare practitioner may order serial estriol samples to look for a trend, whether there is a rise or fall in the estriol level over time.
    • Unconjugated estriol is often measured in the 15th to 20th week of gestation as part of the triple/quad screen.

    In Boys and Men

    Estradiol (E2) and/or estrone (E1) testing in boys and men may be ordered when:

    • A boy has delayed puberty, characterized by delayed development of muscle mass, lack of deepening of the voice or growth of body hair, slow or delayed growth of testicles and penis
    • A man shows signs of feminization, such as enlarged breasts
  • What does the test result mean?

    Normal estrogen results depend upon the sex and age of the person being tested. With women, it also depends upon their menstrual cycle or whether they are pregnant. Reference ranges will vary somewhat between laboratories, both in normal values listed and in units used.

    Increased or decreased levels of estrogens are seen in many metabolic conditions. Care must be used in the interpretation of estrone, estradiol, and estriol results because the levels vary on a day-to-day basis and throughout a woman's menstrual cycle.

    A healthcare practitioner who is monitoring a woman's hormones will be looking at trends in the levels, rising or lowering over time in conjunction with the menstrual cycle or pregnancy rather than evaluating single values. Test results are not diagnostic of a specific condition but give the healthcare practitioner information about the potential cause of a person's symptoms or status.

    Below are conditions with which one might see an increase or decrease of estrogen levels.

    Increased levels of estradiol (E2) or estrone (E1) are seen in:

    Girls and Women:

    Boys and Men:

    Both Women and Men:

    In women, decreased levels of estrogen are seen in:

    • Turner syndrome, an inherited condition in women caused by a missing or abnormal X chromosome and characterized by underdeveloped female sex characteristics
    • Low level of pituitary hormones (hypopituitarism)
    • Dysfunction of the ovaries (female hypogonadism)
    • Failing pregnancy (estriol)
    • Eating disorders such as anorexia nervosa
    • After menopause (estradiol)
    • Polycystic ovary syndrome (PCOS, also called Stein-Levanthal syndrome)
    • Extreme endurance exercise
  • Is there anything else I should know?

    Blood and urine results are not interchangeable. Your healthcare practitioner will choose which estrogen and sample type to test. In addition to blood and urine, estrogen testing is occasionally also performed on saliva or on amniotic fluid.

    Beyond daily and cycle variations, illnesses such as high blood pressure (hypertension), anemia, and impaired liver and kidney function can affect estrogen levels.

  • Do all men have estrogens?

    Yes. Although they are present in amounts far less than in women, they are present and are needed for hormonal balance and the function of other glands.

  • What are estrogen receptors?

    Estrogen receptors are proteins in cells from certain tissues that bind with estrogen. This binding allows estrogen to act on these tissues. Tumors can also have estrogen receptors. Estrogen can stimulate the growth of estrogen receptor-positive tumors in women who have breast cancer. Drugs that block the effect of estrogen may slow the rate of growth of such cancers. See the article on Estrogen/Progesterone Receptor Status for more on this.

  • What are phytoestrogens and environmental estrogens?

    Phytoestrogens are estrogen-like compounds from plant sources. The two main classes are isoflavones, found in soy products, and lignans, found in whole grains and some fruits and vegetables. It has been proposed that these products could be used as an alternative to hormone replacement therapy (HRT). Initial studies have shown the relief of some menopausal symptoms, such as hot flashes, but there is more research yet to be done.

    Environmental estrogens are chemicals, either natural (such as plant sources) or man-made (such as the insecticide DDT), that mimic the effect of estrogen and may cause disorders such as infertility, overgrowth of the endometrial lining, premature breast development, and feminization in young males. They tend to stay in the body for long periods of time and are being studied for their long-term effects.

Health Professionals - Optimal Testing Recommendations

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**This content is intended for healthcare professionals.**

Visit the article For Health Professionals: Estradiol Testing in Men for the full recommendations.

  • Measurement of estradiol in men (and children) should be performed by a sensitive liquid chromatography-tandem mass spectrometry (LC/MS)-based assay.
  • Immunoassay-based estradiol tests perform best at higher concentrations of estradiol and therefore work well for those with levels in the adult-female range.

The content for Optimal Testing: AACC's Guide to Lab Test Utilization has been developed and approved by the AACC Academy and AACC's Science and Practice Core Committee.

View Sources

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