Blood Markers Might Predict Clotting Risk With HRT

ByABC News
March 24, 2008, 2:16 AM

Mar. 23 -- SATURDAY, Dec. 8 (HealthDay News) -- Levels of certain blood markers may increase the risk of clotting in women taking hormone replacement therapy to relieve symptoms of menopause, new research shows.

These markers might need to be considered when deciding whether to take the hormone therapy, said the authors of a study being presented Saturday at the American Society of Hematology annual meeting in Atlanta.

Hormone replacement therapy (HRT) roughly doubles the risk of venous thrombosis (VTE), or blood clots in the veins (most commonly in the legs). The risk is increased even further as the woman ages, and if she is obese or has other risk factors for clotting.

For a woman in her 50s not taking hormones, the risk of developing a VTE is one or two per 1,000 thousand people per year. With hormones, the risk increases to two to four per 1,000 per year.

"The challenge is that women who want to take hormones for relief of menopausal symptoms are at risk for thrombosis," said study author Dr. Mary Cushman, director of the Thrombosis and Hemostasis Program at the University of Vermont, in Burlington. "We wanted to see if we could determine factors that would make the risk of hormones even higher."

The group looked at women who had been part of the Women's Health Initiative (WHI), a large, government-sponsored study which investigated the most common causes of death and low quality of life among postmenopausal women.

The best-known findings are those of clinical trials looking at HRT. Women taking estrogen plus progestin had an increased risk of heart attack, stroke, blood clots and breast cancer than women taking the placebo. Women taking estrogen alone had an increased risk of stroke and blood clots, an uncertain effect for breast cancer and no difference in the risk for heart attack.

For this analysis, 215 women taking hormones who developed VTE were compared with a control group, also taking hormones, who did not develop VTE during a follow-up of about four years.