Estradiol, Free LabCorp

Estradiol is the predominant sex hormone present in females and is also found in lower levels in men. Estradiol is one of three estrogens, the other two being estrone and estriol. Estradiol represents the major estrogen in humans. Estradiol not only impacts reproductive and sexual functioning; but also affects other systems including bone health, heart health, nerves, and metabolism. Estradiol (also known as E2) is the most active of all three estrogens commonly measured in a clinical setting. In women, it is important to compare the relationship between Estradiol and Progesterone in the evaluation of menopausal symptoms such as hot flashes, mood disorders, and aging skin. In men, high levels of estradiol are associated with abdominal fat, enlargement of the prostate, and cardiovascular risk. Estradiol in the body typically binds to proteins. The unbound portion and estradiol that is bound to proteins with low affinity reflects the concentration of free estradiol. Measuring free estradiol levels may correlate better with medical conditions, more so than measuring total estradiol levels.