An estradiol test measures the amount of the hormone estradiol in your blood. It’s also called an E2 test.

Estradiol is a form of the hormone estrogen. It’s also called 17 beta-estradiol. The ovaries, breasts, and adrenal glands make estradiol. During pregnancy, the placenta also makes estradiol.

Estradiol helps with the growth and development of female sex organs, including the:

uterus

fallopian tubes

vagina

breasts

Estradiol helps to control the way fat is distributed in the female body. It’s also essential for bone and joint health in females.

Males also have estradiol in their bodies. Their levels of estradiol are lower than the levels in females. In males, the adrenal glands and testes make estradiol. Estradiol has been shown in vitro to prevent destruction of sperm cells, but its clinical importance in sexual function and development in men is likely less significant than in women.