what is e2
It is also converted from other hormones and external environment precursors. E2 (Estradiol) is the most active estrogen produced by the ovaries before menopause. E3 (Estriol) is the weakest of the three forms of estrogen and is made in the body from other estrogen.hen the ovaries begin to fail, the circulating E2 (Estradiol) levels drop. This drop in the E2 (Estradiol) level is what the physician often measures as a serum E2 (Estradiol) concentration test to determine estrogen levels.