Size of estrogen dose may be critical in determining whether estrogen therapy leads to cardiovascular or kidney disease, mouse study suggests. (2008)
From the article:
For a 60 day period ovariectomized (OVX) mice received the estrogen hormone 17β—estrodial (E2), a drug very similar to that used in treating the symptoms of menopause. The mice received one of four dosing levels every day throughout the study period: a very low (VL) dose (0.001 µg/d); a low (L) dose (0.42 µg/d); a moderate (M) dose (4.2 µg/d); or a high (H) dose (28.3 µg/d).
The researchers found that:
– Moderate and high doses of ERT increased the plasma estrogen levels in the mice more than four fold (4.5). This was associated with fluid retention in the uterus, amounts of protein in the urine, and dilated kidneys.
– By contrast, low doses of E2 restored plasma estrogen to levels similar to the control rats and neither fluid retention nor renal damage was found in this group of mice.
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– Moderate and high doses of E2 also increased atrial natriuretic peptide (ANP), a cardiac hormone that is increased as a marker of severity of heart failure. At low level dosing this did not occur.
– Overall blood pressure and cardiac function were not changed by ERT at any given dose.
[…]
Other factors such as the ratio of estrogen to progestin, the age when the therapy begins and the cardiovascular health_ of the patient when treatment starts may also be important factors to investigate.