Bioidentical Hormones for Menopausal Therapy

Cynthia K Sites


Women's Health. 2008;4(2):163-171. 

In This Article

Use of Bioidentical Progesterone

Progesterone may be added to estrogen as part of menopausal hormone therapy. To increase oral availability, progesterone obtained from yams or soybeans is micronized. This compound, called Prometrium® in the USA, is approved by the FDA and has been reported to prevent endometrial hyperplasia at doses of 200 mg/day for 12 days monthly when conjugated estrogens were also prescribed.[28] The effect of Prometrium on menopausal hot flashes and vaginal dryness, alone or in combination with estradiol, has received little attention. It appears that Prometrium improves sleep quality in postmenopausal women better than synthetic medroxyprogesterone acetate when conjugated estrogens are also used.[29]

Progesterone is also used in transdermal creams or gels compounded with transdermal estrogens by compounding pharmacies. One might think that progesterone is added to prevent endometrial hyperplasia when estrogens are also prescribed, but this is not the case with compounded progesterone because women with a hysterectomy may be prescribed this combined regimen, and natural progesterone, particularly when used as a skin cream, does not reliably prevent endometrial proliferation or endometrial hyperplasia.[30,31,32] In fact, three cases of endometrial cancer have been reported in Australia among women using bioidentical progesterone as troches or skin cream along with estrogen.[33] Advocates for bioidentical progesterone provide the following reasons for adding progesterone to their hormone regimen: beliefs that topical progesterone cream increases libido, effects on climacteric symptoms, prevention of osteoporosis, improvement in mood, effects on thyroid hormones, impact on blood clotting and serum glucose, as well as alteration in fat metabolism.[34,35] Popular books also claim that progesterone cream can eliminate "estrogen dominance secondary to relative insufficiency of progesterone" that is characteristic of various medical conditions, such as breast cancer, uterine fibroids, fibrocystic breast disease, and premenstrual syndrome.[36] However, evidence for the efficacy of transdermal progesterone for these various medical conditions is largely lacking. There appears to be some efficacy for progesterone 40 mg daily plus estradiol 1 mg daily compounded as a transdermal cream for menopause symptoms, but further studies are needed to determine safety.[31]


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