Estradiol (E2)

What estradiol does

In women, estradiol drives the menstrual cycle and supports the lining of the uterus, but its reach is much wider. It helps maintain bone density, keeps vaginal and urinary tissues thick and elastic, affects how the brain regulates temperature and sleep, and influences cholesterol and skin.

In men, a modest amount of estradiol, made when the enzyme aromatase converts testosterone, matters for bone strength, libido and erectile function. Too much can contribute to breast tissue growth.

How it changes at midlife

During perimenopause, estradiol doesn't fall in a straight line. It can swing from high to low from one cycle to the next, which helps explain irregular periods, breast tenderness, headaches and mood shifts. After menopause, the ovaries make very little estradiol, and estrone, a weaker estrogen made in fat tissue, becomes the main form.

Measuring estradiol

An estradiol blood test is one of three estrogen tests labs offer, along with estrone (E1) and estriol (E3). Clinicians may order it to:

• Look into irregular or absent periods, fertility problems or early menopause.
• Evaluate breast enlargement, low libido or erectile problems in men, often alongside testosterone.
• Monitor some forms of hormone therapy, particularly men on testosterone.
• Check for rare hormone-producing tumors.

Reading results

Because estradiol shifts so much across a cycle and through perimenopause, a single result can be misleading, and repeat testing may be needed to see a pattern. Menopause in women over 45 is usually diagnosed from symptoms and the menstrual history rather than an estradiol number.

Estradiol as a medicine

Estradiol is also the estrogen used in most modern menopausal hormone therapy, available as FDA-approved patches, gels, sprays, tablets, vaginal rings and creams, as well as compounded preparations. Systemic estradiol is the most effective treatment for hot flashes and night sweats and helps prevent bone loss.

It carries real risks that need an individual discussion, including blood clots, stroke and, with longer use, breast cancer; clot risk appears lower with skin patches and gels than with pills. If you have a uterus, you also need a progestogen to protect the uterine lining from cancer.

Whether estradiol therapy is right for you depends on your age, how long it's been since your last period, your symptoms and your personal and family history. The Menopause Society notes that the balance of benefit and risk is generally most favorable when treatment starts before age 60 or within 10 years of menopause.