Estradiol (E2)

Estrogens are a group of hormones that play a key role in female reproductive health, including puberty, menstruation, pregnancy, and menopause. However, estrogens are also important for more general bodily functions in both males and females, including healthy cholesterol and blood sugar levels, bone and muscle strength, and brain functions such as the ability to focus.

There are many types of estrogen, but only three types are commonly tested: Estrone (E1), the weakest of the three types, made mostly by body fat and the adrenal glands; Estradiol (E2), the main estrogen in nonpregnant females of childbearing age, mostly made in the ovaries; and Estriol (E3), an estrogen that increases during pregnancy and is made in the placenta.

Estradiol levels naturally rise and fall during the menstrual cycle, which is why this test is often used to check on ovarian function and to track follicle development during fertility treatments.

Though estrogen levels depend on many factors, including sex and age, levels that stay too high or too low may be a sign of a health problem.

A healthy level of estradiol depends on several factors, including your age, your sex, the reason for the test, and where you are in your menstrual cycle.

In premenopausal women, estradiol changes throughout the cycle. It is lowest just after a period (around 15 pg/mL or less), peaks just before ovulation (often around 300 pg/mL or higher), and falls again before the next period. Tracking the rise and fall can help check ovulation and time fertility treatment.

After menopause, estradiol is usually low (often under 30 pg/mL). Very low estradiol over time is linked with bone thinning and fracture risk in both older women and older men.

In men and prepubertal children, estradiol is normally very low. Higher than expected levels in men can lead to breast tissue growth (gynecomastia) and may suggest obesity, liver disease, certain medicines, or, less often, an estrogen-producing tumor.

In women, low estradiol with high FSH and LH suggests the ovaries themselves aren't making enough hormone (for example, with menopause or premature ovarian failure). Low estradiol with low FSH and LH suggests a problem with signaling from the brain (the hypothalamus or pituitary), which can be caused by stress, intense exercise, very low body weight, or certain medicines.

Because estrogen levels change so often, you may need to be tested more than once. Talk with your provider about what your results mean for you.