Menopause: Types of Estrogen

The three major naturally occurring estrogens in women are estrone (E1), estradiol (E2), and estriol (E3). Estradiol (E2) is the predominate form in nonpregnant females, estrone is produced during menopause, and estriol is the primary estrogen of pregnancy. In the body these are all produced from androgens through actions of enzymes.

Types

Steroidal

•  From menarche to menopause the primary estrogen is 17β-estradiol. In postmenopausal women more estrone is present than estradiol.
•  Estradiol is produced from testosterone by aromatase and estrone from androstenedione.
•  Estrone is weaker than estradiol.

Premarin, a commonly prescribed estrogenic drug, contains the steroidal estrogens equilin and equilenin, in addition to estrone sulfate but due to its health risk, more genetic estrogen named Progynova (estradiol valerate) are now more often prescribed.

Nonsteroidal

A range of synthetic and natural substances have been identified that also possess estrogenic activity.

•  Synthetic substances of this kind are known as xenoestrogens.
•  Plant products with estrogenic activity are called phytoestrogens.
•  Those produced by fungi are known as mycoestrogens.

Unlike estrogens produced by mammals, these substances are not necessarily steroids.

Menopause

Menopause starts as the functioning of the ovaries begin to change. The ripening and release of the ovum (which, during the reproductive years leads to ovulation and then menstruation if pregnancy does not occur), becomes unpredictable. Ovulations start to be skipped, and the menstrual cycle starts to become less reliable in timing. As these changes become more pronounced, periods start to be skipped, and other perimenopausal symptoms may appear.

 

After a number of years of erratic functioning, the ovaries almost completely stop producing progesterone and two out of the three estrogen hormones: estradiol and estriol. Estrone is one estrogen which is still produced in reasonable amounts in post-menopausal women. Testosterone levels decrease; however, a decrease in testosterone levels begins gradually in young adulthood. Testosterone levels are thought not to drop significantly during the menopause transition because the stroma of the postmenopausal ovary and the adrenal gland still continue to secrete small amounts of testosterone, even during post-menopause.

Menopause is the end of the reproductive years rather than the beginning, and thus it is the opposite of menarche, nonetheless it can usefully be compared with that event: the menopause transition years are in many ways similar to puberty in that women experience hormonal fluctuations which usher in a new stage of life. Similar to pubescent girls, menopausal women are often unfamiliar or uneducated about the types of bodily changes they are undergoing, and may require time to adjust to the accompanying effects of these changes.