Monday, February 29, 2016
Testosterone deficiency in women?
While there is substantial evidence of the importance of endogenous and exogenous estrogen in reproductive health and chronic disease, there is little consideration of androgens in women's health. In the Michigan Bone Health Study (1992–1995), the authors examined the correlates of testosterone concentrations in pre- and perimenopausal women (i.e., age, menopausal status, body composition, and lifestyle behaviors) in a population-based longitudinal study including three annual examinations among 611 women aged 25–50 years identified through a census in a midwestern community. Current smokers had the highest testosterone concentrations with decreasing values in former and nonsmokers (p = 0.0001). Body composition measures (body mass index, body fat (%), weight (kg), lean body mass (kg), and fat mass (kg)) were significantly and positively associated with total testosterone concentrations in a dose-response manner. Hysterectomy with oophorectomy was associated with significantly lower testosterone concentrations. Alcohol consumption, physical activity, and dietary macronutrient intake were not associated with testosterone concentrations. This is one of the first studies to examine correlates of serum testosterone concentrations in anticipation of the growing interest in the role of androgens in women's health. The greater circulating levels of testosterone in obese women and smokers suggest that testosterone concentrations should be considered in the natural history of disease conditions where obesity and smoking are risk factors, including cardiovascular disease.
Who may be affected?
Most of the current clinical experience with androgens and androgen deficiency has been in post-menopausal women who complain of decreased sexual desire after cessation of menses, and are not helped by estrogen replacement therapy alone. The question of androgen deficiency has largely been ignored in pre-menopausal women. Testosterone levels have usually been measured in this population only when looking for excess production in women complaining of facial hair, loss of scalp hair, infertility, or acne. A recent presentation at the 2000 Female Sexual Function Forum meeting in Boston revealed that 36 premenopausal and 38 postmenopausal women complaining of decreased libido also had decreased total and free plasma testosterone levels as well as decreased levels of DHEA-S.
Guidelines for assessing androgen deficiency
Assays for plasma total testosterone have been available for over 40 years, and the levels are shown to decrease with age in women, as they do in men. The relatively newer free testosterone assay has been in use for a decade, and whether by equilibrium dialysis or by direct radioimmunoassay, it is felt to be more accurate because it measures the amount of testosterone available for activity in the tissues.
However, very little data are available on normal ranges for these assays. Even the known data, using total testosterone, suffer from the general flaw that none of the women used for the normal ranges were screened for any type of sexual problems, including decreased sexual desire. Until better data exist, a plasma total testosterone level of <25 ng/dL in women under 50 years old, and <20 ng/dL in women aged 50 or older, is indicative of androgen deficiency. For the free testosterone assay by direct radioimmunoassay, the guide is used that in women under the age of 50, a level of <1.5 pg/mL, and in women over the age of 50, a level of <1.0 pg/mL, is indicative of androgen deficiency. If the values are even slightly above the levels mentioned, it should be considered borderline, and a clinical trial of androgen may be in order if the symptoms are suggestive. More accurate and consistent data are available for the measurement of DHEA-S. This hormone also decreases with age. A recent analysis has suggested two age-related curves, one for lean and one for obese women. According to a clinic’s experience, in women under the age of 50 with DHEA-S levels of <150 ng/dL a diagnosis of decreased adrenal DHEA production is appropriate. Similarly, the diagnosis of adrenal DHEA production should be considered in women aged 50 or older whose DHEA-S levels are <100 ng/dL.
There are no clear guidelines for evaluating women who might have androgen deficiency. Only recently has there been acknowledgement of the need for clear guidelines for measuring decreased androgen levels. In reality, women may develop symptoms of androgen deficiency at any age, from their teen years through late adulthood. The chief symptom is often a decrease in sexual interest, which is not often acknowledged. Another common symptom is fatigue, a symptom associated with many clinical conditions and therefore not likely to increase your suspicion of androgen deficiency. Ask female patients about decreased sexual desire and sexual fantasies, as many are reluctant to mention these problems. In many instances physicians have been quick to ascribe sexual problems to anxiety, depression, premenstrual syndrome, or lack of sleep-especially during the child-rearing years. Peri-menopausal women may complain of decreased sexual desire at the onset of their life cycle changes, attributing it to these changes. This may be the time to test for androgen deficiency. Also, in the postmenopausal woman, test the testosterone levels if decreased sexual desire does not improve after 6 months of estrogen replacement or if she declines such therapy.