Estradiol (E2)
Primary female sex hormone for cycle regulation, bones, heart, and cognition
Also known as
Definition
Estradiol (17β-estradiol, E2) is the most potent and prevalent estrogen, primarily produced in the granulosa cells of the ovaries. In men it arises from the aromatization of testosterone in adipose tissue and the liver. E2 regulates the female menstrual cycle, ovulation, uterine lining development, bone maintenance, cardiovascular protection, and cognitive function. Values vary substantially with cycle phase, age, and hormonal status.
| Parameter | Value |
|---|---|
| Unit | pmol/l (pg/ml) |
| Reference Range | Women: Follicular phase: 100–590 pmol/l | Ovulation: 370–1,850 pmol/l | Luteal phase: 180–670 pmol/l | Postmenopause: < 110 pmol/l | Men: 50–180 pmol/l (14–50 pg/ml) |
Agree on your personal target range with your doctor.
Conversion: 1 pmol/l = 0.272 pg/ml. US labs: pg/ml (follicular phase 27–161 pg/ml).
↓ What a low value means
Low estradiol in women: ovarian insufficiency, menopause, hypothalamic amenorrhea (underweight, overtraining, stress), hyperprolactinemia. Symptoms: hot flashes, vaginal dryness, osteoporosis, cardiovascular risk, cognitive impairment, sleep disturbances. Low E2 in men: rare, associated with bone density loss and erectile dysfunction.
↑ What a high value means
Elevated estradiol in women: PCOS with estrogen excess, overweight (elevated aromatase), xenoestrogens, hormone-producing tumor. In men: obesity, liver cirrhosis, anabolic steroid use, estrogen-producing tumor. Symptoms: gynecomastia, loss of libido, mood swings, water retention, infertility.
✓ What can influence this value
In women, estradiol is influenced mainly by the course of the cycle, pregnancy, menopause, hormonal contraceptives, hormone replacement therapy, body weight, and alcohol consumption (alcohol can increase aromatase). In men, estradiol is formed mainly from testosterone via aromatase; overweight, because adipose tissue contains aromatase, can raise the value. Liver diseases and certain medications also act on the value. The assessment is made by the treating doctor.
When to test
Women: on cycle days 3–5 for baseline; periovulatory (around days 12–14) and in the luteal phase (around day 21). For menopause, hormonal disorders, or fertility diagnostics. Men: for gynecomastia, reduced libido, or as part of a hormone panel with testosterone and SHBG.
Frequently asked questions
What is meant by estrogen dominance, and can it be detected in the blood? +
Estrogen dominance is a widely used term, but not a recognized medical diagnosis. It usually refers to a ratio in which estradiol outweighs progesterone, not necessarily high absolute estrogen levels. There are no uniform criteria or cut-offs for it, and a single measurement of E2 and progesterone cannot establish such a ratio, because both hormones fluctuate widely across the cycle. Your doctor interprets the result.
Why do estradiol values fluctuate so much? +
Estradiol follows the menstrual cycle: low in the early follicular phase, a strong rise toward ovulation (ovulatory peak), mildly elevated in the luteal phase, then declining. Additionally, there is circadian variation and influences from stress, diet, and exercise. The cycle day of measurement is therefore part of interpreting the value.
Do men need estrogen? +
Yes. Men require estradiol for bone density (E2 is an important bone-protective factor in men too), libido, sperm maturation, and cardiovascular protection. Too little E2 in men leads to bone density loss and erectile dysfunction; too much E2 (often from obesity) leads to gynecomastia and loss of libido.
What happens to estradiol during menopause? +
With the cessation of ovarian function, E2 falls from approximately 200–500 pmol/l to < 110 pmol/l. Adipose tissue takes over as the primary production site (aromatization of androgens). Hot flashes, sleep disturbances, vaginal dryness, and mood changes are typical consequences. Whether and how treatment is given is decided by your doctor.
Estradiol (E2)
Sources
Last updated: May 28, 2026
This information is for orientation only and does not replace medical advice. Reference ranges can vary by laboratory, method and country.