An estradiol test is a blood test that measures the amount of estradiol in your blood. It may also be called an E2 test.
Estradiol is a form of the hormone estrogen. In women, estradiol is produced in the ovaries, adrenal glands, and the placenta during pregnancy. Estradiol helps with the growth of the female sex organs, including the uterus, Fallopian tubes, vagina, and breasts. It also helps to control the way fat is distributed in the female body.
Males also have estradiol in their bodies, but in lower levels than females. In males, estradiol is produced in the adrenal glands and testes. Estradiol helps with fertility and sex drive in males.
An estradiol test may be ordered if female or male sex characteristics are not developing at the normal rate. An estradiol level that is higher than normal indicates that an individual may be going through puberty earlier than usual. This is a condition known as precocious puberty.
Lower levels of estradiol may indicate that an individual is going through puberty late. The test may also be ordered to look for problems with the adrenal glands or to determine if treatment for hypopituitarism (decreased function of the pituitary gland) is working.
A doctor may order estradiol testing to look for causes of:
- abnormal menstrual periods
- abnormal vaginal bleeding
- infertility in women
Your doctor may also order an estradiol test if your menstrual cycle has stopped and you are experiencing symptoms of menopause.
The estradiol test can indicate how well the ovaries are working. Therefore, your doctor may also order this test if you have symptoms of an ovarian tumor. Symptoms include:
- trouble eating
- pain in the lower abdominal and pelvic area
If you are pregnant or on fertility treatments, your doctor may order this test to help monitor your progress.
An estradiol test usually cannot be used on its own to diagnose conditions. However, the results of this test may help your doctor decide if further testing is necessary.
Estradiol levels that are higher than normal may suggest:
- early puberty
- tumors in the ovaries or testes
- gynecomastia (development of breasts in men)
- hyperthyroidism (over activity of the thyroid gland)
- cirrhosis (scarring of the liver)
Lower-than-normal levels of estradiol may suggest:
- Turner syndrome (a genetic disorder in which a female has only one X chromosome instead of two)
- ovarian failure (the ovaries stop functioning before the age of 40, also called premature menopause)
- polycystic ovarian syndrome (a hormone disorder with a wide range of symptoms, believed to be a leading cause of poor fertility in women)
- depleted estrogen production (caused by low body fat)
- eating disorders (such as anorexia nervosa)
- hypogonadism (the ovaries or testes don’t produce enough hormone)
An estradiol test is a blood test. This may also be called a blood draw or venipuncture. A technician called a phlebotomist will perform the blood test.
Blood is usually drawn from a vein on the inside of the elbow or the back of the hand. To begin, the technician will use antiseptic to clean the area from which your blood will be drawn. This helps prevent infection. The technician will then wrap an elastic band called a tourniquet around your upper arm. This causes the vein to swell with blood. The technician will then insert a needle into your vein and draw blood into a tube.
The amount of blood that is being drawn depends on the number of blood tests your doctor has ordered. The blood draw will only take a couple of minutes. The process may be slightly painful—most people report a pricking or burning sensation.
When the technician is finished drawing blood, he or she will apply pressure to stop the bleeding. A bandage will then be applied, and your blood sample will be sent for testing in a laboratory.
Certain factors can affect estradiol levels. It is important that you and your doctor discuss these factors. He or she may ask you to stop taking a certain medication or change the dose before your test.
Estradiol levels can also vary throughout the day and with a woman’s menstrual cycle. As a result, your doctor may ask you to have your blood tested at a certain time of day or at a certain time in your cycle. Conditions that can affect estradiol levels include:
- hypertension (high blood pressure)
- kidney problems
- reduced liver function
Medications that can affect estradiol levels include:
- oral contraceptives (birth control pills)
- estrogen therapy
- phenothiazines (used to treat schizophrenia and other mental disorders)
- tetracycline (an antibiotic)
- ampicillin (an antibiotic)
The risks associated with having your blood drawn are low. Risks include:
- multiple punctures due to trouble finding a vein
- excessive bleeding
- lightheadedness or fainting
- hematoma (an accumulation of blood under the skin)