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  Back Blood-tests Explained


Estradiol


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 health 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 in your arm or a 24-hour urine sample

Test Preparation Needed?

None

The Test Sample

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 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 and luteal phase. 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 41. 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.

How is the sample collected for testing?

A blood sample is drawn from a vein in the arm or a 24-hour urine sample is collected.

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

No test preparation is needed, 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.

The Test

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:

  • May sometimes be ordered serially to help monitor a high-risk pregnancy; when it is used this way, each sample should be drawn at the same time each day.
  • An unconjugated estriol test is one of the components of second trimester maternal serum screening. Decreased levels have been associated with various genetic disorders, including Down syndrome, neural tube defects, and adrenal abnormalities.

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 health 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 health 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 health 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:

  • Early (precocious) puberty
  • Tumors of the ovary or adrenal glands

Boys and Men:

  • Enlarged breasts (gynecomastia)
  • Tumors of the testicles (testicular cancer) or adrenal glands
  • Delayed puberty

Both Women and Men:

  • Hyperthyroidism
  • Cirrhosis

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)
  • PCOS (Polycystic ovarian syndrome, Stein-Levanthal syndrome)
  • Extreme endurance exercise

Is there anything else I should know?

Blood and urine results are not interchangeable. Your health 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.

Some drugs, such as glucocorticosteroids, ampicillin, estrogen-containing drugs, phenothiazines, and tetracyclines, can increase estrogen levels in the blood. Glucose in the urine and urinary tract infections can increase levels in the urine. Drugs that may decrease levels include clomiphene and oral contraceptives.



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