The story of the history of estrogen illustrates the historical progression of medical knowledge, from laboratory and clinical observation, through basic and clinical experimentation, to current successful medical management, an interesting marriage of empiricism and technology.
Our bodies efficiently make our natural hormones. Cholesterol from our diet is converted into a family of progesterones, which then become our androgens, such as testosterone, androstenedione, and dehydroepiandrosterone (DHEA). Androgens are important since they are the substrate for all of the estrogens in our body. The ovaries alone convert testosterone to estradiol (E2), the most powerful of the estrogens. Fat cells can convert androstenedione to other weaker estrogens, including estrone (E1), only 40% as active as estradiol, and estriol (E3), only 10% as active as estradiol. Since menopausal symptoms seem to arise with falling estrogen levels, estrogen has been sought as treatment of these symptoms.