1. Bio-identical hormones are “natural”
In the HRT field, the term “bio-identical” is considered a marketing term by the FDA. This term is used simply to refer to the fact the hormone matches the chemical and molecular structure of hormones that are produced by the human body. A common list of bio-identical hormones would be estradiol, progesterone, testosterone, estriol, and DHEA. A sample of hormones that would NOT be included on this list include medroxyprogesterone, norethindrone, levonorgestrel, and conjugated equine estrogens. Bio-identical hormones used in HRT are typically produced by modifying a compound that comes from soy or yam. This conversion does not happen in vivo (in the human body) and must be done in a laboratory by a FDA approved chemical manufacturer. Thus, while the sources of the hormone are natural, and its role in the body is natural, the molecule itself is synthesized.
2. Bio-identical hormones are only available from compounding pharmacies
Many commercial, FDA approved products currently prescribed by physicians contain bio-identical hormones. Estradiol is available as oral tablets (Estrace), topical patches (Vivelle, Minivelle, Climara), topical gels (Estragel) and vaginal cream (Estrace). Progesterone is available as oral capsules (Prometrium) and vaginal cream (Prochieve). Testosterone is available for men (in male doses) as topical gel (AndroGel, Testim) and underarm solution (Axiron). Physicians chose the compounded hormone option only when a commercial product is not available or does not meet the patient’s needs. A few examples of when compounded HRT can be a good alternative: when the medication itself (estriol) is unavailable or the combination desired (combining estradiol and progesterone into one topical or vaginal cream) is not produced or a specific dosage is needed (female testosterone dosages) .
3. Bio-identical hormones are “safe”
Estrogen is a proliferative hormone and a woman’s exposure to it over her lifetime can increase her risk of breast cancer, regardless of whether or not the hormone is produced by her own body, taken in the form of a synthetic estrogen or administered in a bio-identical form. The safety of HRT can be increased by the combination of hormones given and the importance of prescribing progesterone instead of a synthetic progestin. In the infamous WHI study, where an increased risk of breast cancer and cardiovascular disease was found, the study subjects were being given medroxyprogesterone acetate (a progestin), NOT progesterone. Unfortunately, the message extrapolated from that study has lead to many reports of progesterone increasing the risk of breast cancer. In studies where progestins and progesterone have been compared head to head, the progestins have repeatedly been found to increase breast cell proliferation while progesterone has not. Other recent large studies have shown that alternative routes of administration, such as topical or vaginal, would be another factor that physicians and patients could use to reduce cardiovascular risks associate with oral estrogens.
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Fournier, A., Berrino, F., & Clavel-Chapelon, F. (2008). Unequal risks for breast cancer associated with different hormone replacement therapies: results from the E3N cohort study. Breast Cancer Res Tr, 107(1), 103-111.
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