Glossary term

Estradiol

Also known as 17β-estradiol - E2

The dominant estrogen - swings 50-500 pg/mL across your cycle and crashes in perimenopause.

Estradiol (E2) is the most biologically active estrogen. Ovarian production drives 50-500 pg/mL swings across the menstrual cycle; post-menopause, levels drop below 30 pg/mL. Beyond reproduction, estradiol protects bone density, cardiovascular lining, cognition, and sleep architecture. Test on cycle day 3 for baseline or day 21 for luteal context; for perimenopause staging, pair with FSH. HRT protocols dose transdermal or oral estradiol under provider review - history of breast or endometrial cancer, unexplained DVT, or liver disease flag the decision. Run the Women's Hormone panel before acting on symptoms.

Symbol

E2

Unit

pg/mL

Typical range

Cyclic: ~50-500 pg/mL; post-menopausal baseline typically under 30 pg/mL.

Medically reviewed byDr. Lena Okafor, MD

Medical Director - updated April 2026 - How we review