Monday, February 7, 2011

Natural and Bio-Identical Estrogen

Theoretically, if we have a dose of a bioidentical estrogen that is equivalent in strength to the dose of the conventional estrogen, the cardiovascular benefit or risk should be the same.Nonetheless, any hormone therapy that is considered to be an alternative to the leading form of therapy (conjugated equine estrogens, i.e., Premarin) must at some point be compared in order to prove its worthiness and acceptability among patients and health-care practitioners. A few studies have looked at oral micronized estradiol alone or in combination with bio-identical progesterone and compared it to conjugated equine estrogens (CEE) plus medroxyprogesterone acetate (MPA) to evaluate possible effects on CAD. Ten menopausal women, administered the natural estrogen/progesterone combination, experienced a decrease in total cholesterol.
In contrast, this parameter did not change significantly at 12 months over the initial cholesterol readings in the five women who were given CEE and MPA. Both groups experienced an increase in HDL cholesterol.Another study reported the results of a combination pill containing 2 mg of oral micronized estradiol, 1 mg of estriol, and 1 mg of a synthetic progestin in 265 women, who were followed for over four years;serum cholesterol and triglyceride levels decreased significantly, but HDL levels were not measured.
Estriol is the other natural estrogen that can be used either alone or in combination with estradiol (called bi-est) or with estradiol and estrone (called tri-est). Little is known about what estriol may or may not do with regard to CVD. However,two studies indicate positive effects of estriol administration on lipid profiles and cardiac function. Japanese researchers found that 2 mg per day of estriol was effective in decreasing total cholesterol and triglycerides and increasing HDL levels in elderly women (age 70 to 84), but not in middle-aged postmenopausal women (age 50 to 65).The other study followed postmenopausal women using estriol and found an increase in their cardiac function and improved blood flow in the extremities.387 Even so, I would not currently consider estriol a viable approach for treating or preventing heart disease. When it comes to cardiovascular disease, I contend that ethically, practitioners using bio-identical hormone therapy must have the same benefit-risk conversation with patients as a conventional practitioner who prescribes the typical Premarin/Provera would have. That said, in my opinion,there is enough evidence at this point that oral micronized progesterone is more cardiac friendly on lipids and coronary arteries than are the synthetic progestogens or progestin (such as Provera).Other than this point, I would advocate for following the current guidelines from the North American Menopause Society and their Position Statement on HRT in Menopausal Women:
Data from studies such as the WHI and the Heart and Estrogen/progestin Replacement Study (HERS) should be extrapolated only with caution to women younger than 50 years of age who initiate HT. The data should not be extrapolated to women experiencing premature menopause (under 40 years of age) and initiating HT at that time.
Premature menopause and premature ovarian failure are conditions associated with earlier onset of CHD [coronary heart disease],but there are no clear data as to whether ET [estrogen therapy] or Estrogen /progestogen therapy] will reduce morbidity or mortality from these conditions. The benefit-risk ratio may be more favorable for younger women.Nonoral routes of administration of ET/EPT may offer advantages and disadvantages,but the long-term benefit-risk ratio has not been demonstrated. Differences would be related to the role of the first-pass hepatic effect, the hormone concentrations in the blood achieved by a given route, and the biologic activity of component ingredients. There is some evidence that transdermal 17 beta-estradiol does not increase the level of C-reactive protein, and also that it may be associated with lower risk of deep venous thrombosis than oral estrogen. The effect of ET on CHD and stroke is not yet clear. ET does not have a significant effect on stroke risk in post menopausal women with known ischemic cerebrovascular disease,but for healthy older women, effects of ET on stroke risk are not clear. However, unless confirming data become available, ET should not be used for primary or secondary prevention of these conditions.

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