Clinical Significance

The determination of estradiol is utilized clinically to identify fertility disorders, gynecomastia, estrogen producing ovarian and testicular tumors and in hyperplasia of the adrenal cortex. Further clinical indications are the monitoring of fertility therapy and determining the time of ovulation. Estrogen secretion is biphasic during the menstrual cycle. Normal estradiol levels are lowest at menstruation and into the early follicular phase (25-75 pg/mL) and then rise in the late follicular phase to a peak of 200-600 pg/mL just before the LH surge , initiating ovulation. As LH peaks, estradiol begins to decrease before rising again during the luteal phase (100-300 pg/mL). If conception does not take place, estradiol falls further to its lowest levels, thus initiating menses. If conception occurs, estradiol levels continue to rise, reaching levels of 100-500 pg/mL during the first trimester, 5000-15,000 pg/mL during the second trimester and 10, 000 – 40,000 pg/mL during the third trimester. At menopause estradiol levels remain low.