Estradiol (E2)

What is estradiol (E2)?

Estradiol is the most potent of the estrogen hormones, and in women most of it is secreted by the developing follicles in the ovaries. It supports the growth of the uterine lining, the development of breast tissue, the regulation of the menstrual cycle and the maintenance of bone health. In men, it is present in much smaller amounts, formed mostly by the conversion of testosterone in tissues such as fat tissue, and it plays a role in bone health and sperm production.

In women, estradiol levels change markedly throughout the cycle: they are low in the first days of the period, reach their peak before ovulation and rise somewhat again in the second half of the cycle. After menopause, they decrease permanently. During pregnancy, with the contribution of the placenta, they rise to very high levels. The test is performed on serum using immunological methods, and the result is reported in pg/mL; for this reason, the cycle day on which the blood was drawn must always be known.

When is the estradiol test ordered?

Your doctor most often orders estradiol together with FSH and LH to assess how the ovaries are working. In assisted reproduction treatments such as IVF, it may be repeated every few days to monitor follicle development. It may also be ordered to monitor the effect of treatment in women receiving hormone-suppressing therapy. In men and children, it provides guidance when conditions that disrupt hormonal balance are being investigated.

• Irregular periods, absent periods or abnormal uterine bleeding
• Difficulty getting pregnant and assessment of ovarian function
• Monitoring of IVF and ovulation treatments
• Symptoms of menopause or early menopause, such as hot flashes
• Early or delayed puberty in girls
• Breast enlargement (gynecomastia) or sexual function problems in men

How do you prepare for the estradiol test?

You do not need to fast for estradiol, and blood is usually drawn in the morning. In women who menstruate, the timing of the test is very important: day 2 or 3 of the period is usually preferred for assessing ovarian function and baseline hormone levels, while for treatment monitoring the day specified by your doctor applies. The day bleeding starts counts as day 1 of the cycle.

Birth control pills, hormone therapy and some fertility medications directly affect the result; if you use these medications, be sure to mention them when the sample is collected. High-dose biotin, which may be found in hair and nail supplements, can also interfere with immunological measurements, so you may need to pause it before the test after consulting your doctor. Blood is drawn from a vein in the arm; a Curavita nurse can come to your home or workplace on the specified cycle day to collect the sample.

What does the estradiol result mean?

In women, an estradiol result can only be interpreted according to the phase of the cycle in which the blood was drawn; the same value may be normal in one phase and noteworthy in another. Higher-than-expected levels may be due to the ovulation period, ovarian cysts, hormone therapy or, rarely, estrogen-secreting tumors. Because a high estradiol on day 2–3 of the period can suppress FSH and make the ovarian reserve look better than it actually is, the two tests are evaluated together.

Low levels may be seen in menopause, premature ovarian insufficiency, loss of periods due to excessive weight loss or intense exercise, and pituitary gland problems. In men, high levels may be associated with excess weight, liver disease or testosterone use. Reference values vary by laboratory, age, sex and cycle phase; the ranges of the laboratory that performs the test are also shown separately on this page. The meaning of your result should be determined by your doctor together with your cycle day, symptoms and other hormone tests.