Estrogens are hormones that occur naturally in women and men and are also made synthetically. Estrone (E1), estradiol (E2), estriol (E3) are the three most common naturally occurring estrogens.
In women, estrogens are the main hormone responsible for sexual and reproductive development. Estrogen is produced by the ovaries, adrenal glands, and in fat tissue. During pregnancy, the placenta produces estrogen which helps prepare the breasts for milk production and maintain the pregnancy. Estrogens also have critical roles in male sexual function, including modulation of libido, erectile function, and spermatogenesis. In males, estrogens are produced by the adrenal cortex, in fat tissue, and in small amounts by the testes. Testosterone is also converted into estrogen by the enzyme, aromatase. Excessive production of estrogen in men causes feminization.
Estrogens may be used to treat symptoms of conditions associated with estrogen deficiency such as amenorrhea and menopause. They may be used to suppress lactation and in men to treat androgen-dependent cancers such as prostate cancer. Estrogens are also used as contraceptives, in combination with progestins (another class of sex hormones).
