1015. Estradiol (E2)

Estradiol (E2) is a steroid hormone produced primarily in the ovaries, in the placenta during pregnancy, and in smaller amounts in the testes and peripheral tissues from hormonal precursors. It plays an important role in the development and functioning of the reproductive system. The estradiol test measures its level in the blood and may be recommended for menstrual cycle disorders, difficulties conceiving, premature or delayed puberty, breast enlargement in men, and for monitoring certain types of treatment.

Estradiol is the main and most potent estrogen in women of reproductive age. It is involved in sexual development, regulation of the menstrual cycle, and the functioning of the reproductive system; it affects follicular maturation, ovulation, and preparation of the inner lining of the uterus for a possible pregnancy. Estradiol also contributes to the maintenance of bone tissue and affects a number of other processes in the body.

In women before menopause, estradiol is produced primarily in the ovaries, while during pregnancy the placenta becomes an important source of estrogens. Estradiol in men is also produced, but in significantly smaller amounts, primarily through the conversion of testosterone in body tissues, as well as directly in the testes. Despite its lower levels, it is involved in the functioning of the reproductive system and in maintaining bone strength.

The laboratory estradiol test measures its concentration in blood serum. The test may also be referred to as an estrogen level test. However, estrogens are a group of hormones, whereas this test measures a specific form of estrogen – estradiol (E2).

The test may be part of the laboratory evaluation of menstrual cycle disorders, sexual development, ovarian or testicular function, as well as the causes of difficulties conceiving. Depending on the purpose of the evaluation, a doctor may recommend measuring estradiol together with FSH (follicle-stimulating hormone), LH (luteinizing hormone), progesterone, anti-Müllerian hormone (AMH), testosterone, sex hormone-binding globulin (SHBG), or calculating the free androgen index (FAI). The test result does not establish a diagnosis on its own. It is interpreted together with symptoms, health status, and the results of other examinations.

Normal estradiol levels in women and men

The term “normal estradiol” refers to reference ranges – the range against which the test result is compared. It helps assess whether the estradiol level corresponds to the expected values for a particular sex, age, and health status. The limits of this range depend on the testing method and equipment, so the reference values provided by the laboratory on the test report should be used for interpretation. A result outside the reference range does not always indicate the presence of a disease. If necessary, a doctor may recommend a repeat test or additional hormonal and instrumental examinations.

High and low estradiol: interpretation of test results

Estradiol levels are interpreted taking into account sex, age, phase of the menstrual cycle, pregnancy, menopause, use of hormonal medications, and the purpose of the evaluation. Therefore, the same result may be interpreted differently in different situations.

High estradiol in women

Estradiol levels naturally increase before ovulation and during pregnancy. The level may also increase while taking hormonal medications.

If the increase is not related to the phase of the menstrual cycle, pregnancy, or use of hormonal medications, it may be seen in premature sexual development, certain disorders of ovarian function, liver diseases, and rare tumors that produce estrogens. The cause of an elevated level cannot be determined based on a single test result.

Low estradiol in women

After menopause, estradiol levels naturally decrease. Before menopause, low estradiol may be observed with reduced ovarian function or impaired regulation of ovarian function by the hypothalamus and pituitary gland (the hypothalamus is a part of the brain, while the pituitary gland is an endocrine gland; together, they regulate ovarian function). Other possible causes include very low body weight or inadequate nutrition, excessive physical activity, severe or prolonged illnesses, and the use of certain medications.

Estrogen deficiency, that is, an insufficient level of estrogens, may be accompanied by irregular or absent menstrual periods, hot flashes, and vaginal dryness. Over time, bones may also lose strength. However, these symptoms may have other causes as well.

A single estradiol test result cannot determine the cause of a low level or establish a diagnosis of premature ovarian insufficiency. For this purpose, the estradiol level is evaluated together with FSH, symptoms, menstrual cycle characteristics, and the results of other examinations.

Estradiol in men

If estradiol is elevated in a man, the result is interpreted taking into account testosterone levels, symptoms, and the use of medications. An elevated level or an altered ratio of estradiol to testosterone may be observed in gynecomastia (breast enlargement), excess body weight, certain liver diseases, use of hormonal medications, and rare hormone-producing tumors (tumors whose cells produce excessive amounts of hormones).

A low level may be associated with reduced testosterone production, impaired conversion of testosterone to estradiol, or the use of certain medications. Prolonged estradiol deficiency may negatively affect bone tissue.

The estradiol test may be recommended to assess reproductive system function, determine the causes of hormonal disorders, or monitor treatment. The need for testing and the timing of the test are determined based on symptoms and the purpose of the evaluation.

The test may be recommended for women:

• in cases of irregular or absent menstrual periods;
• in cases of difficulty conceiving (infertility);
• to assess ovarian function together with other hormone measurements;
• as part of a comprehensive evaluation when premature ovarian insufficiency is suspected;
• to monitor follicular maturation and the ovarian response to stimulation during infertility treatment;
• in the presence of hot flashes, vaginal dryness, and other symptoms of possible estrogen deficiency;
• when disorders associated with excess estrogen are suspected.

The test may be recommended for men:

• in cases of breast enlargement (gynecomastia);
• as part of a comprehensive evaluation when a couple is experiencing difficulty conceiving, as recommended by a doctor;
• in cases of disorders of sexual development;
• when hormonal disorders or hormone-producing tumors are suspected.

The test may also be recommended:

• when there are signs of premature or delayed sexual development in children and adolescents;
• as part of an evaluation when disorders of sex hormone production are suspected;
• as part of a comprehensive evaluation in cases of reduced bone density or osteoporosis if a doctor suspects a hormonal cause;
• to monitor estradiol levels during treatment that may affect estrogen production.

• Venous blood

In order to exclude factors that may affect the test results, we recommend to follow the preparation rules: