Testosterone is a vital hormone in women, circulating in nanomolar concentrations. Not only is testosterone a precursor for estradiol biosynthesis in the ovaries and extragonadal tissues, but testosterone acts directly via androgen receptors throughout the body. Levels decline with age in women with the greatest fall in total and free testosterone occurring before the menopause. Large RCTs involving naturally and surgically postmenopausal women presenting with hypoactive sexual desire disorder (HSDD) demonstrate that testosterone therapy, with/without concurrent estrogen therapy, improves the quality of the sexual experience. More recent studies demonstrate the use of testosterone therapy improves sexual wellbeing in premenopausal women with HSDD. The effects appear not to be mediated by aromatization of testosterone to estrogen. The other potential benefits of testosterone in women include favorable effects on bone density, muscle mass, vascular endothelial function and cognitive function.
Data from observational studies mostly show an inverse relationship between testosterone and CVD risk. Published RCTs indicate that non oral testosterone therapy does not adversely affect plasma lipids or other CVD risk markers. The relationship between endogenous testosterone production and breast cancer risk remains contentious, with recent studies indicating no relationship. There does not appear to be an association between testosterone and endometrial cancer, or other malignancies.
Testosterone use has not been approved other than for surgically menopausal women on estrogen therapy in Europe. Despite this, the use of testosterone by women is widespread, with vast numbers of women using testosterone preparations developed and marketed for men, testosterone preparations compounded on individual prescriptions as oral lozenges and creams, and testosterone implants. Hence there is a clear need for a testosterone therapy delivering an appropriate female dose to be approved, so that women have the option of using a product formulated for women.
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Funding: This work was supported, however funding details are unavailable.