It’s not just hormones, it’s how you take them. Two new studies report that post-menopausal women who used estrogen patches or gel instead of pills had a lower risk of blood clots. Many women find that Hormone Replacement Therapy (HRT) offers relief from some symptoms of menopause, like hot flashes and vaginal dryness. But HRT has come under fire recently, as some research has suggested that its possible risks—including heart attack, breast cancer and stroke—outweigh its benefits. Estrogen therapy is also known to increase the risk of venous thromboembolism, or, in layman’s terms, blood clots. These clots are especially likely in the lung, and can be fatal.
In one of the new studies, however, women taking oral estrogen were more than three times as likely to have a blood clot than women using the estrogen patch or gel, or women taking no estrogen at all. No difference in blood clot risk was found between estrogen and estrogen-plus-progestin therapy.
Researchers stressed that more inquiries need to be made into how the patch affects other HRT risks.
Patches are generally placed on the abdomen or buttocks, and replaced once or twice weekly. Women can swim or bathe easily while wearing the patch.
The first study, published in August in the French journal The Lancet, involved 155 women who had experienced a blood clot and 381 women who had similar characteristics but hadn’t had clots. Researchers accounted for other risk factors, and still found the three-to-one increased risk of blood clots for pill users.
For the second study, published a month later in the American Heart Association's journal Arteriosclerosis Thrombosis and Vascular Biology, researchers randomly assigned 196 post-menopausal women to take a placebo pill, estrogen-plus-progestin pill or estrogen-plus-progestin patch for six months.
Women who took oral estrogen had higher markers of blood coagulation activity than the others, researchers reported. The oral estrogen also significantly altered the effect of an "activated protein C," a blood compound, on the regulation of thrombin, a clotting factor.
"Taken together, these data provide a plausible biologic mechanism to the clearly demonstrated association between oral estrogen and venous thrombosis," the research team wrote.
"This randomized trial highlights the importance of the route of estrogen administration in prescribing postmenopausal hormone therapy," Dr. Emmanuel Oger, the leader of the team, told Reuters Health.
