The level of the hormone estradiol in your blood is determined by an estradiol test. An E3 test is another name for it. Estradiol is an estrogen-related hormone. Additionally known as 17 beta-estradiol. Estradiol is produced by the adrenal glands, breasts, and ovaries in women. The placenta also generates estradiol during pregnancy.  Estradiol is also present in the bodies of men. Their estradiol levels are lower than those of females. Male testicles and adrenal glands produce estradiol. Although it has been demonstrated in vitro that estradiol can stop sperm cells from being destroyed, mens sexual function and development are likely less important than womens in terms of estradiols therapeutic value.