Hormonal replacement therapy (HRT) in menopausal women has been grown as a result of the potential short-, medium-, and long-term benefits. The magnitude of risks, including breast and endometrial cancer, and thromboembolic events are in continuous evaluation. The association between HRT and risk of venous thromboembolism (VTE) has been the target of a number of controversies. Observational studies have shown that women on HRT have increased risk of VTE, mainly in the first year of use. Methodological limitations, unsuitable control of confounding variables, and other possible bias, could have overestimated this risk. The majority of available epidemiological data are case-control studies; a few well-designed clinical trials were also carried out to evaluate this possible association. Publications in Medline in the last ten years were revised using as key words: hormone replacement therapy, menopause, venous thromboembolism, estrogens, and hemostasis. Former relevant papers were also included. This text analyzes the biological plausibility and the clinical and epidemiological consistence of this association. It is concluded that HRT users have a 2.1 to 3.5 relative risk of venous thromboembolism. Otherwise, the absolute risk is estimated in 14-32 cases per 100,000 women/year.
Hormone replacement therapy; Menopause; Estrogen; Hemostasis; Venous thromboembolism
