Estrogen

Estrogen is actually a combination term in humans. Normal human estrogen is made of three separate hormones: estradiol (the main workhorse estrogen), estriol (elevated in pregnancy but we don’t know much else about it), and estrone (the stored estrogen, and highly carcinogenic). When we speak about estrogen, we generally mean estradiol. When estradiol is taken orally, the liver converts about half of it to estrone, which is what makes estradiol pills so dangerous. However, when applied topically (to the skin) or in subcutaneous (under the skin) pellets, it is not dangerous and generally well-tolerated. Low levels of estradiol can cause hot flashes, night sweats, mood swings, impatience, depression, vaginal dryness and certain infections. The brain is a very big user of estradiol.