Research

Hormonal

Oral conjugated estrogen (0.625 mg/day) and combined oral estrogen/progestin (0.625 mg estrogen + 2.5 mg medroxyprogesterone acetate) significantly reduce plasma PAI-1 levels by approximately 50% in postmenopausal women, thereby enhancing systemic fibrinolysis.

For postmenopausal women, oral hormone replacement therapy (specifically conjugated estrogen) significantly lowers PAI-1, a protein that inhibits blood clot breakdown, by about half. This suggests oral estrogen may improve the body's ability to dissolve clots. However, transdermal (patch) estrogen does not appear to have this effect, and the net cardiovascular benefit is uncertain because oral estrogen might also increase other clotting risks in some women. This is not a standalone treatment for heart disease prevention without considering individual risk factors.

GoodSupportsHIGH confidence
Conjugated estrogen, both alone and in combination with medroxyprogesterone acetate, reduced mean plasma levels of PAI-1 from 32 ng per milliliter to 14 ng per milliliter (P<0.001) and from 31 ng per milliliter to 15 ng per milliliter (P=0.003), respectively... Conjugated estrogen, alone or combined with progestin therapy, reduced PAI-1 levels by approximately 50 percent in postmenopausal women and was associated with enhanced systemic fibrinolysis.
Kwang Kon Koh et al. · New England Journal of Medicine · 1997

Why this rating

Randomized, crossover, double-blind design with a small sample size (n=50).

Source

Effects of Hormone-Replacement Therapy on Fibrinolysis in Postmenopausal Women

Kwang Kon Koh et al. · New England Journal of Medicine · 1997

DOI 10.1056/nejm199703063361002

crossover · n=50Cited 376×
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DOI resolved against Crossref · corpus check 2026-06-10

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