What is the predominant form of estrogen after menopause?

After menopause, the predominant form of estrogen that replaces estradiol is estrone. Estradiol is primarily produced by the ovaries during a woman's reproductive years, but after menopause, ovarian function declines significantly, leading to a decrease in estradiol levels.

Estrone, on the other hand, is derived mainly from the conversion of androgens in adipose tissue and the adrenal glands and becomes the primary circulating estrogen. This shift is significant because estrone can still exert estrogenic effects in the body, which can influence various physiological processes and health conditions in postmenopausal women.

In contrast, progesterone is not an estrogen; it is a hormone involved in the menstrual cycle and pregnancy, and while its levels also decrease after menopause, it does not play a role in estrogenic effects. Androstenedione is an androgen, which can be converted into estrone but is not an estrogen itself, making it less relevant in the context of predominant forms of estrogen post-menopause.

Thus, the understanding of estrone's role as the main form of estrogen after menopause highlights the changes in hormone regulation that occur during this transition.