Part of “CHAPTER 100 – MENOPAUSE“

With follicular depletion, steroid production by ovarian follicles falls. The predominant estrogen produced by ovarian follicles is estradiol. When estradiol production ceases, the symptoms of menopause ensue. However, estrogen production in postmenopausal women does not stop completely; instead, production at low levels continues throughout life (Fig. 100-1 and Fig. 100-2). The estrogens produced after the menopause derive from androgens, specifically androstenedione, coming from the adrenal gland and, in part, from the stroma of the ovary. The androgens are converted into estrone by tissues such as the liver, the kidneys, and peripheral fat.3 Estrone is a weaker estrogen than estradiol. The ratio of estrogens changes from the premenopausal situation, in which estradiol predominates over estrone, to the postmenopausal one, in which estrone predominates. Because androgens are converted to estrogens in peripheral fat, overweight women convert more of their adrenal androgens to estrogens than women of normal weight.4 Thus, overweight women are less at risk for diseases associated with estrogen deficiency, such as osteoporosis, but are more at risk for diseases associated with estrogen excess, such as endometrial cancer.5 Sex hormonebinding globulin is also relatively decreased in obese women, thereby increasing the proportion of bioactive (free) estradiol. As for androgens, the androstenedione concentration is little changed postmenopausally, but its peripheral conversion to estrone rises from 1.3% to 2.7%. Serum levels of testosterone are slightly lower than in the premenopausal state. Nevertheless, there is relative androgen excess in the postmenopausal compared with the premenopausal situation (Table 100-1).