Estradiol (E2)
What is it?
Estradiol is the main estrogen in reproductive-age women and is present at lower levels in men. It regulates the menstrual cycle, bone health, and many tissues. Values change sharply with cycle phase, pregnancy, and menopause.
Normal ranges
Wide lab-specific and phase-specific ranges. Follicular phase often ~30–100 pg/mL; mid-cycle peak higher; postmenopausal often <30 pg/mL. Adult men roughly ~10–40 pg/mL — always compare to your lab’s reference interval.
Units: pg/mL (pmol/L in SI)
Causes of deviations
Low levels:
Menopause, ovarian insufficiency, some medications (e.g., aromatase inhibitors), hypogonadism contexts.
High levels:
Ovulation or pregnancy, estrogen therapy, some ovarian tumors, obesity-related increased aromatase in men.
When to see a doctor
If levels are unexpected with symptoms (cycle changes, hot flashes, gynecomastia, galactorrhea) or when monitoring hormone therapy — coordinate with an endocrinologist or gynecologist.
This information is for educational purposes and does not replace medical advice.
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