Venous thromboembolism and hormone replacement therapy.

There is evidence that postmenopausal women who take hormone replacement therapy develop biochemical hypercoagulability, expressed by increased activity of coagulation enzymes. Such effects are observed whether estrogen is given alone or in combination with progestogens, orally or transdermally. Two recent randomized, double-blind clinical trials have shown that hormone replacement therapy leads to an increased risk of venous thromboembolism (VTE) in postmenopausal women. Generally, in women with no additional risk factors for VTE, the excess risk due to hormone replacement therapy is rather small. However, women with a history of VTE should not be prescribed hormone replacement therapy.