The addition of testosterone to hormone therapy in women after menopause enhances their sexual function. However, it may also reduce HDL cholesterol (the "good" cholesterol) in women, according to a systematic review of current evidence.
"If the reduction in HDL had been associated with an increase in triglycerides [fatty acids] or LDL cholesterol it would be of great concern," said Dr. Susan Davis, professor of medicine at Monash University, Melbourne, Australia, and study co-author "However, as an isolated finding the significance is difficult to interpret." She added, "Testosterone has not been found to alter other coronary heart disease risk factors."
The review appears in the most recent issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates medical research. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.
The study team reviewed 23 randomized clinical trials involving 1,957 patients who had testosterone added to their hormone replacement therapy (either estrogen or combined estrogen/progestin) for an average of six months. Testosterone was given orally in a majority of the studies in doses of either 1.25 mg. or 2.5 mg. Participants completed questionnaires that measured their sexual activity and libido, and were assessed for other side effects.
Other benefits and side effects measured in the studies included in the review included sense of well-being, unexplained fatigue, breast cancer, mood changes, acne and increased hair growth; none were significant enough to be linked definitively to the addition of testosterone to hormone replacement therapy.
In the United States, about 37.5 million women ages 40 to 49 are reaching or currently at menopause, according to the Centers for Disease Control and Prevention.
Menopause generally begins around age 40, inducing declining levels of the hormones estrogen and progesterone which are known to keep the vagina and uterus healthy; estrogen is also involved in the health of bones and keeping HDL at healthy levels. Changes brought on by menopause can cause unwelcome side effects in women such as "hot flashes" and problems with mood, sleep, memory and joint stiffness.
Many women also experience changes in sexual function; the genital area can become drier and thinner during and after menopause, making sexual intercourse painful and undesirable. Also, the menopausal years bring on a decrease in sex drive and slower sexual response in some women.
Although testosterone, a sex hormone produced by the endocrine system, is thought of as a male hormone, women secrete small amounts of it as well. According to background information in the review, testosterone has previously been shown to improve sexual function, bone mineral density, muscle mass, increased lean body mass, mood, energy and psychological well being.
However, there may be side effects in further studies of testosterone use, according to Nanette Santoro, M.D., professor and director of the Albert Einstein College of Medicine's Division of Reproductive Endocrinology. "It is possible that long-term side effects that have not been observed with six month's use could occur," Santoro cautioned.
"Long-term use of testosterone in women concerns include voice changes, increased body and facial hair, acne and other undesirable defeminizing side-effects; these have not been reported with short-term use." Santoro adds. In men, according to Santoro, large doses can cause growth and cancer of the prostate, blood clotting problems and increased red blood cell counts.
Davis said that unwanted side effects, such as acne and hairiness, would be noted by women taking testosterone and that the does of testosterone dose could be reduced appropriately.
The authors do caution that adding testosterone to HT is not a panacea for sexual dysfunction in women and that a comprehensive approach is recommended. "Because of the complex nature of female sexual dysfunction it is often difficult to establish the meaningful steps in treatment," they write. "Treatment options for sexual dysfunction include identification of correctable causes, education and counseling, and medical therapy."
They add that limitations of the review include the small number of studies suitable for inclusion and the fact that some of the studies included various interventions.
Davis has acted as a consultant for companies that have tested testosterone therapies for women: Solvay Pharmaceuticals, Acrux Ltd, Cellegy, Procter & Gamble and Organon and has received honoraria for lectures sponsored by the last two companies.