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: 370–1850 pmol/l | Luteal phase: 180–670 pmol/l | Postmenopause: < 110 pmol/l | Men: 50–180 pmol/l (14–50 pg/ml) |
| Optimal Range (lab2go) | Women (follicular phase): 200–500 pmol/l (lab2go Optimum Zone) | Men: 70–150 pmol/l (optimal for libido, bones, and mood without estrogen excess) |
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, estrogen dominance, 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.
✓ How to optimize this marker
Women: normalize weight, optimize sleep, reduce alcohol (alcohol stimulates aromatase). Men: weight loss with overweight (reduces aromatase in adipose tissue), ensure zinc intake (aromatase inhibition), optimize testosterone. For estrogen dominance: cruciferous vegetables (indole-3-carbinol, DIM).
When to test
Women: on cycle days 3–5 for baseline; periovulatory (around day 12–14) and in 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 estrogen dominance and how do I recognize it in blood work? +
Estrogen dominance describes an unfavorable ratio of estradiol to progesterone, not necessarily absolutely high estrogen. In blood work this is reflected by elevated E2 with low progesterone (progesterone/estradiol ratio < 100:1 in the luteal phase). Evaluating SHBG, testosterone, and cortisol also helps.
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 must always be noted.
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. HRT can be individually considered for symptoms.
Sources
Last Reviewed: May 28, 2026 · sina
This information is for orientation only and does not replace medical advice. Reference ranges can vary by laboratory, method and country.