Estradiol
Also called E2, 17-beta estradiol
Estradiol, also called E2, is the most potent form of estrogen and the main estrogen the body makes during the reproductive years. An estradiol blood test measures how much of it is circulating. It is one of three estrogens commonly tested, alongside estrone (E1) and estriol (E3).
In women, estradiol is made mostly by the ovaries, where it drives the menstrual cycle and also supports bone and brain health. Men make it too, in smaller amounts, and need it: estrogen supports bone, sex drive and reproductive health in men, and both too little and too much can cause problems, including low libido at one end and enlarged breast tissue and erectile difficulty at the other.
Why it matters after 45
For women, estradiol falls through perimenopause and, after menopause, estrone becomes the main estrogen the body makes; perimenopause is one of the situations in which estradiol is tested. Testing is also used to monitor menopausal hormone therapy. For men, the American Urological Association recommends measuring estradiol before testosterone therapy in men with breast symptoms or enlarged breast tissue.
Where it comes up
- High estradiol in womenwhat a raised result can mean and how it is interpreted
- High estradiol in menwhy it rises and when it matters
- When to test hormones in perimenopausewhy timing changes what a result means
- Estradiolthe treatment page for prescribed estradiol
- Gynecomastiathe breast change in men that prompts an estradiol test
Related terms
References
- MedlinePlus. Estrogen Levels Test. U.S. National Library of Medicine. https://medlineplus.gov/lab-tests/estrogen-levels-test/
- Cleveland Clinic. Estrogen. https://my.clevelandclinic.org/health/body/22353-estrogen
- American Urological Association. Evaluation and Management of Testosterone Deficiency (AUA Guideline). https://www.auanet.org/guidelines-and-quality/guidelines/testosterone-deficiency-guideline
Definitions here are educational and are not medical advice. They explain what a term means; the pages linked above cover what it means for you, and a clinician reviews your own results. Editorial & medical review policy · All glossary terms