Estradiol (High Sensitivity)

Estradiol is the most potent natural estrogen in humans. It regulates  reproductive function in females, and, with progesterone, maintains pregnancy. Most estradiol is secreted by the ovaries (non-pregnant women), although the testes (in men) and adrenal cortex (in men and women) secrete small amounts. During pregnancy, the placenta produces most of the circulating estradiol. Monitoring estradiol levels is essential during in vitro fertilization, because the timing of recovery of oocytes depends on follicular development, which in turn depends on the estradiol level