Bioidentical Hormones for Menopausal Therapy
"Bioidentical hormones" is a term created by the lay media to refer to chemicals derived from plants that are modified to be structurally identical to endogenous human hormones. These compounds include estradiol, estrone, estriol, progesterone, testosterone and dehydroepiandrosterone when prescribed for menopausal women. Patients assume bioidentical hormones are natural and safer than synthetic hormones with regard to the risk of developing breast cancer and other diseases, but there is little evidence to support this belief. Proponents of this therapy also support the use of salivary hormone measurements to adjust doses of these hormones instead of adjustment based on improvement or lack of improvement in menopausal symptoms. In this review, the rationale behind the use of bioidentical hormones is discussed, along with the evidence supporting the use of compounded and FDA-approved bioidentical products.

Vasomotor symptoms (hot flashes and night sweats) affect two-thirds of all women as they transition into menopause and often for years beyond that time, often severely diminishing the quality of their lives. Other symptoms, such as menopause-related vaginal dryness, contribute to reduced sexual functioning. Traditional therapy with products manufactured by pharmaceutical companies containing estradiol, conjugated estrogens, progestins, progesterone and testosterone has been readily available for patients. Technically, pharmaceutical products containing estradiol, progesterone and testosterone are "bioidentical" in that they contain compounds identical in structure to endogenous hormones. Since the publications of the Women"s Health Initiative and the Heart and Estrogen/Progestin Replacement Study (HERS) in the USA, and with the encouragement of celebrity self-help books and the internet, women have become skeptical of traditional pharmaceutical products prescribed by physicians and sought "natural" or "bioidentical" alternatives made by compounding pharmacies. Animal data suggested that estriol-containing compounds may be safer than those containing estradiol with respect to causing breast cancer, so compounds such as Biest (20% estradiol and 80% estriol) and Triest (10% estradiol, 10% estrone and 80% estriol), made by compounding pharmacies, have increased in popularity, despite no evidence for efficacy or side effects of this treatment for menopausal symptoms. In addition, compounding pharmacies may add progesterone, testosterone and dehydroepiandrosterone (DHEA) to these regimens. We will review the evidence for the efficacy and safety of bioidentical hormones for menopausal symptoms, both those made by pharmaceutical companies and those made by compounding pharmacies, so that practicing clinicians can more easily counsel patients who ask about these regimens.