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Bioidentical hormone replacement therapy (BHRT), also known as bioidentical hormone therapy or natural hormone therapy, is a term referring to the use of hormones that are identical on a molecular level with endogenous hormones in hormone replacement therapy. It may also be combined with blood and saliva testing of hormone levels, and the use of pharmacy compounding to obtain hormones in an effort to reach a targeted level of hormones in the body. A number of claims by some proponents of bioidentical hormone replacement therapy have not been definitively established through scientific testing. Specific hormones used in BHRT include estrone, estradiol, progesterone (which are available both in FDA-approved manufactured products and as pharmacy-compounded products), testosterone, dehydroepiandrosterone (both testosterone and dehydroepiandrosterone have some stringent limits placed on their availability and approval in Canada and the United States), and estriol (which is available in Europe but is not approved in Canada and the United States). Custom-compounded BHRT is a practice almost wholly restricted to the United States.〔 BHRT is a form of alternative medicine, and has been promoted as a panacea for many diseases in addition to being a means of relieving the symptoms of menopause and/or reducing the risk of osteoporosis (historically, the goals of hormone replacement therapy in allopathic medicine). There is little evidence to support many of these claims; the hormones are expected to have the same risks and benefits of comparable approved drugs for which there is an evidence base and extensive research and regulation. The exception is progesterone, which may have an improved safety profile than artificial progestogens, though direct comparisons with progestins have not been made. Risks associated with the process of compounding bioidentical hormones are not clearly understood. In addition, the accuracy and efficacy of saliva testing has not been definitively proven, and the long-term effects of using blood testing to reach target levels of hormones have not been researched. The International Menopause Society, American Congress of Obstetricians and Gynecologists, Society of Obstetricians and Gynaecologists of Canada, The Endocrine Society, the North American Menopause Society (NAMS), United States Food and Drug Administration, American Association of Clinical Endocrinologists, American Medical Association, American Cancer Society and the Mayo Clinic have released statements that there is a lack of evidence that the benefits and risks of bioidentical hormones are different from well-studied nonbioidentical counterparts; until such evidence is produced the risks should be treated as if they are similar; and that compounded hormone products may have additional risks related to compounding. A major safety concern in bioidentical hormone replacement therapy is that there is no requirement to include package inserts, despite the potential for serious adverse effects (including life-threatening adverse effects) associated with HRT. This can lead to consumers being deceived (and harmed), as they are misled into believing that any hormone-related problems and dangers are exclusively related to nonbioidentical hormones, and that BHRT is therefore safe and has no side effects. In reality, the risks of bioidentical hormones have not been studied to the extent of nonbioidentical hormones, so the risks are not well understood. Regulatory bodies require pharmacies to include important safety information with conventional hormone replacement therapy (CHRT) via package inserts. ==History== Bioidentical hormones were first used for menopausal symptom relief in the 1930s,〔 after Canadian researcher James Collip developed a method to extract an orally active estrogen from the urine of pregnant women and marketed it as the active agent in a product called Emmenin.〔{〕 It was supplanted on the market when its manufacturer, Ayerst (later Wyeth Pharmaceuticals), began producing the more easily manufactured conjugated equine estrogens in 1941 under the brand name Premarin; by 1992, Premarin was the most widely prescribed drug in the United States. In the 1970s, research and reports indicating risks from synthetic conjugated estrogens began to appear. Investigation determined that the addition of a progestogen to estrogen treatment reduced the risks. As early as 1980, the ''British Medical Journal'' (now ''BMJ'') recommended oral bioidentical progesterone as an option when side effects from synthetic progestogens otherwise mandated discontinuing treatment. Starting in 1980, side effects caused by synthetic progestin use prompted more research into bioidentical progesterone. In May 1998 the FDA approved Prometrium, an oral bioidentical progesterone product produced by Solvay Pharmaceutical. Physicians John R. Lee and Jonathan Wright were pioneers in the area of BHRT.〔 Lee authored several popular books on BHRT and promoted custom-compounded BHRT, with the goal of achieving what he called a "natural hormone balance". He based this goal on the clinical testing of saliva to establish where "deficiencies" existed, though agencies such as the FDA and the American Congress of Obstetricians and Gynecologists state that blood and saliva testing is unreliable and biologically meaningless.〔 Lee also believed that progesterone acted as a panacea〔 and general health tonic for many health conditions; he based his claims on anecdotal data rather than peer-reviewed research,〔 and there have been no clinical trials demonstrating this to be true.〔 Wright also authored a popular book on BHRT;〔 he promoted a triple-estrogen formula he called "Triest", which combined the most common three estrogens (of over 25 types) found in human females: estriol, estradiol and estrone. Previous bioidential formulas had used only estradiol. This triple formula was based on a single unpublished study whose conclusions did not take into account how estrogens are processed and excreted in the body—particularly how the liver processes oral estrogens, converting most of them to estrone. No followup was performed by Wright to replicate these observations.〔 Wright may have been the first proponent of BHRT to use the term "bioidentical"—the word he coined to describe unpatentable, plant-derived molecules he believed were identical to human hormones. However, no structural crystallographic evidence has been used to support the idea that these molecules are actually identical to endogenous human hormones. When the Women's Health Initiative's reports on the unappreciated risks of equine estrogens were released, many prescribers of BHRT used Wright's assertions (and his terminology) to proclaim the superiority of bioidentical molecules despite a lack of scientifically supported evidence. Following the publication of a popular book written by actress Suzanne Somers in 2006, the term "bioidentical" gained more prominence in popular consciousness as a "poorly understood new adjective" regarding hormone replacement therapy.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Bioidentical hormone replacement therapy」の詳細全文を読む スポンサード リンク
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