Estradiol (E2)
Estradiol is the most biologically active estrogen, produced mainly by the ovaries in premenopausal women and in smaller amounts by adipose tissue, adrenal glands, and testes. Levels vary dramatically across the menstrual cycle (lowest during menses, peak just before ovulation, high in the luteal phase), pregnancy, and after menopause (very low). Estradiol is measured in fertility workup, menopause assessment, ovarian stimulation, and suspected estrogen-producing tumors.
Reference Ranges
Male
10 – 50
pg/mL
Female
15 – 350
pg/mL
Child
Consult pediatrician
Reference ranges may vary by laboratory. Always compare with the range printed on your lab report.
What Low Levels Mean
In premenopausal women, unexpectedly low estradiol suggests ovarian dysfunction, pituitary dysfunction (hypothalamic amenorrhea from stress, weight loss, over-exercise), hyperprolactinemia, or premature ovarian insufficiency. In postmenopausal women, low estradiol is expected. In men, very low estradiol is uncommon and rarely pursued.
What High Levels Mean
High estradiol in non-pregnant premenopausal women may reflect ovarian hyperstimulation, an estrogen-producing ovarian tumor (granulosa cell tumor), or exogenous estrogen. In men, elevated estradiol can cause gynecomastia — causes include obesity (aromatization in fat tissue), liver disease, hyperthyroidism, testicular tumors, and exogenous estrogen. In pregnancy, estradiol rises progressively and reaches very high levels.
Frequently Asked Questions
When should estradiol be measured in the cycle?
It depends on the question. For ovarian reserve or baseline assessment, day 2–3 (early follicular) — should be low (<50 pg/mL). For ovulation induction monitoring, daily during stimulation. For luteal function, day 21. For menopause confirmation, any time — persistently low estradiol with high FSH confirms menopause.
What estradiol level confirms menopause?
Estradiol below 30 pg/mL combined with FSH above 30 mIU/mL, in a woman with at least 12 months of amenorrhea, confirms menopause. Estradiol alone is unreliable for this — transient low levels occur normally in some cycles. Symptoms (hot flashes, vaginal dryness) are often more informative than lab values.
Why would a man have a high estradiol?
Men produce small amounts of estradiol through aromatization of testosterone in fat tissue, liver, and other organs. High estradiol in men can cause gynecomastia and affect fertility. Common causes: obesity (more aromatization), chronic liver disease (impaired clearance), hyperthyroidism, hCG-secreting tumors, testicular tumors, and anabolic steroid use with aromatization.
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nmol/LThis information is for educational purposes only and should not replace professional medical advice. Always consult your doctor for interpretation of your test results.
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