Estrogen

The three main estrogens

When people say 'estrogen,' they usually mean one of three molecules:

• Estradiol (E2): the strongest and the main estrogen from puberty to menopause, made mostly by the ovaries.
• Estrone (E1): a weaker estrogen made largely in fat tissue from other hormones. It becomes the main estrogen after menopause.
• Estriol (E3): the weakest, produced in large amounts by the placenta during pregnancy. In menopause care it's used mainly in vaginal creams.

What estrogen does

In women, estrogen drives puberty and the menstrual cycle and prepares the uterine lining. Beyond reproduction, it helps keep bones dense, supports the thickness and moisture of vaginal and urinary tissues, affects cholesterol, influences mood and sleep, and plays a part in how the brain regulates body temperature.

In men, estrogen is made mainly by converting testosterone with an enzyme called aromatase. It helps maintain bone, libido and erectile function. Too much, as can happen with obesity or excess testosterone, can lead to breast tissue growth.

What happens when estrogen falls

Through perimenopause, estrogen swings unpredictably, then settles at a much lower level after the final period. The drop is behind many familiar changes: hot flashes and night sweats, sleep disruption, vaginal dryness and painful sex, more urinary symptoms and infections, faster bone loss and shifts in cholesterol. Some symptoms ease with time; vaginal and urinary changes tend to persist or worsen without treatment.

Estrogen as treatment

Estrogen therapy is the most effective treatment for bothersome hot flashes and night sweats and helps prevent bone loss. It comes as pills, skin patches, gels, sprays and vaginal products. Low-dose vaginal estrogen treats vaginal and urinary symptoms with very little absorbed into the bloodstream.

Systemic estrogen has risks that depend on your age, health and the type of product. They include blood clots and stroke and, with combined therapy over several years, a higher chance of breast cancer. If you have a uterus, estrogen must be paired with a progestogen to prevent endometrial cancer. Experts generally see the most favorable balance when therapy starts before 60 or within 10 years of menopause, and the decision is always individual.

Testing estrogen

Blood tests can measure estradiol, estrone or estriol separately. They're useful in specific situations, such as early menopause, fertility questions or men with breast enlargement, but they don't need to be checked to diagnose menopause in most women over 45, and levels vary considerably from day to day during perimenopause.