Most women are aware of that estradiol levels change throughout her lifetime, specifically because of her menstrual cycle. From the initial increase of estradiol that ushers in menarche (when a woman starts her menstruating) to the decrease at menopause, fluctuating estradiol levels are core to being a woman. What many don’t know is that androgens, like testosterone, also change across the lifespan and may impact many of the same functions that estradiol does, albeit in different ways. Researchers are finding that endogenous androgens may play an important role in women’s health, but much less is known about their fluctuation across the life cycle. This topic was extensively reviewed by a group of Japanese scientists.
Androgens, (DHEA, DHEAS, testosterone, DHT, Androstenedione and Androstenediol) are often mistakenly referred to as the male hormones because of their role in male sexual development. Similarly, the estrogens (estrone, estradiol estriol) are frequently referred to as the female hormones. While it is true that males have higher androgen concentrations and females have higher concentrations of the estrogens, it bears repeating that both males and females have androgens and estrogens. Indeed, testosterone, is the precursor for estrone and estradiol. Without testosterone, there would be no estradiol. For more information on the interplay of androgens and estrogens read the following articles: Androgen Deficiency in Women, Let’s Talk Hormones: Common Misconceptions, What Makes a Woman Different from a Man and Menopause and High Blood Pressure.
Androgens and Women’s Health
The role of androgens in postmenopausal women has been investigated by a number of researchers. The decline of androgen levels with ovarian failure and following oophorectomy have sparked the hypothesis that decreased testosterone is related to diminished libido. Indeed, research on the topic has shown a correlation between lower testosterone and diminished libido. The research shows that female androgen deficiency is linked to decreased sexual receptivity and pleasure and also dysphoric mood, reduced motivation and chronic unexplained fatigue. Clinical signs include bone loss, decreased muscle mass and strength, adipose tissue redistribution, decreased sexual hair and changes in cognition or memory.
Like estradiol, testosterone production slows with age, with circulating concentrations declining by 28% by the time women are 85 years old. Because testosterone is a precursor to estradiol synthesis, researchers are finding that the ratio of testosterone to estradiol (T/E) is an important marker of health. The T/E gradually increases during the menopausal transition and increases significantly in postmenopausal stages.
DHEA and DHEAS Other Important Androgens
Dehydroepiandrosterone (DHEA) and its sulfate (DHEA-S) are steroid hormones mainly produced by the adrenal gland. Approximately, 50% of DHEAS is secreted by the adrenals. In women, 20% is secreted by the ovaries, while the remaining amount is derived from circulating DHEA-S. Changes in DHEA-S levels with age differ among races. In the current study, circulating DHEA-S level showed the lowest rate of decline with advancing age in Japanese women and the greatest decline with advancing age in Caucasians.
There are many causes of low testosterone level in women including dysfunction of the hypothalamic pituitary axis, surgical or medical oophorectomy, surgical or medical adrenalectomy, premature ovarian failure, Cushing’s Syndrome, radiation and /or chemotherapy and thyroid disease. Determination of the root cause of low androgen production in women is important because appropriate treatment can improve the quality of life in many women. A recent longitudinal study has indicated that higher testosterone levels may contribute more severe depressive symptoms in women during the menopausal transition.
On the other hand, lower DHEA-S level has been shown to be associated with degree of depressive symptoms in women aged 49-65 years. Androgens also play an important role in bone physiology. Postmenopausal women with hip fracture were found to have significantly lower free testosterone level. The mechanism by which estrogens can promote the growth of breast cancer has been clearly shown. However, the role of androgens is less clear. It has been reported that high levels of both testosterone and estradiol in serum precede breast cancer in postmenopausal women. An analysis of worldwide prospective studies showed strong associations of testosterone and DHEAS with breast cancer risk in postmenopausal women.
Extreme levels of circulating androgens, whether high or low, may have negative effects on women’s health. An excess endogenous testosterone level may be associated with unfavorable lipid profiles, insulin resistance and development of breast cancer in postmenopausal women. On the other hand, insufficient testosterone leads to impairment in sexual drive, reduced libido, and depressed mood. For optimal physiological and psychological health in women, circulating testosterone levels should be within normal ranges. Sensitivity to androgen may be different in various tissues even if the range is narrow. It may be beneficial to not only measure the levels of estradiol but also testosterone and DHEA or DHEAS in postmenopausal women to better understand underlying health-related issues.