What Is a Serum Estradiol Test?

A serum estradiol test is a blood test that is used to evaluate whether or not the adrenal glands, placenta, and ovaries are functioning properly. It may also be used to evaluate the possibility of ovarian tumors, to monitor the effectiveness of hormone replacement therapy in menopausal woman, or to monitor women who may have a high-risk pregnancy. Women who are trying to become pregnant, but who are experiencing fertility problems, may also have a serum estradiol test to evaluate follicle development prior to a fertilization procedure. Some men may also undergo this blood test to help diagnose tumors that produce estrogen.

Normal estradiol levels in women before they undergo menopause are between 30 to 400 picograms per milliliter (pg/mL). After menopause, a woman may have an estradiol level between 0 to 30 pg/mL. A normal range of estradiol in men is considered to be between 10 to 50 pg/mL.

If a serum estradiol test indicates that a patient falls outside the normal range of estrogen, this does not automatically mean that they have a medical condition. While it can aid in a diagnosis, the test does not necessarily point to a definitive cause of abnormal estrogen levels. Many other factors can influence a patient's estrogen levels, including natural daily fluctuations. For example, the daily level of estrogen in a woman will vary, depending on her menstrual cycle and whether she is pregnant. In addition, extreme endurance athletes will also have typically lower estrogen levels, as will those who have the eating disorder anorexia.

While many factors can influence the test results, having a lower or higher than normal estrogen level depicted in a serum estradiol test can help the doctor explore possible diagnoses. Patients with a lower level may suffer from a condition like ovarian failure, Turner syndrome, or polycystic ovarian syndrome (PCOS). Lower levels may also indicate a failing pregnancy, hypogonadism, or hypopituitarism, which occurs when hormone production in the pituitary gland is decreased. Patients with too much estrogen may suffer from a condition such as hyperthyroidism, cirrhosis, or gynecomastia, which occurs when a male has enlarged breasts. Higher levels may also indicate a tumor in the adrenal gland, ovaries, or testes.

Some drugs can also affect levels, so patients who are about to undergo a serum estradiol test should inform the doctor of all medications they take. Birth control pills and hormone replacement therapy can both affect the results of this test. Before drawing blood, the doctor will wrap a band around the upper arm and sterilize the skin. He will then insert a needle to collect the blood and send the sample to the laboratory for testing. Infrequently, patients undergoing a serum estradiol test may experience fainting, excessive bleeding, or an infection.