A high level of white blood cells circulating through the body seems to mark an increased risk of heart disease. These cells, deployed as part of the immune system to defend the body against illness, are a sign of inflammation, which health experts have connected to numerous conditions, including heart trouble. Most of these heart studies, however, have focused on men, which is a problem because heart disease seems to act differently in women. Researchers from the Women's Health Initiative Research Group remedied that imbalance, following a large group of women, and learned that white cells are indeed something worth watching.

What the researchers wanted to know: Does a high white blood cell count increase a woman's risk of heart disease?

What they did: The researchers gave health examinations, took medical histories, and analyzed blood samples for more than 66,000 postmenopausal women. Based on the levels of white cells in their blood, they divided the women into four groups, from the lowest level of white blood cells to the highest. The researchers followed the women for six years, with annual surveys asking them if they had been treated for heart attack, stroke, or other heart diseases, and examined the women three years after their initial visit to look for signs of heart disease.

What they found: Women in the group with the highest white blood cell count had a more than 200 percent increase in risk of death from heart disease compared with women with the lowest levels, even after the researchers controlled for other risk factors. The women with the most white cells also had a 50 percent increase in both heart disease overall and total mortality. The women with the second-highest or third-highest levels did not have significant increase in their risk, meaning that there may be a threshold after which the presence of white blood cells signals danger.

What it means to you: Because screening for levels of white blood cells is an easy and noninvasive process, this test could be used in the future to help determine if women are at risk of heart disease. Nieca Goldberg, a New York cardiologist, says that many women, especially older women, have their white blood cells analyzed regularly and that a high count usually signals to a doctor that something is wrong. While this test will not be the sole predictor of heart problems, she says, it could "help mark a woman's risk for heart disease."

Caveats: This study tells us only that white blood cells are linked to an increased risk of heart disease; it does not show that an increased level of white blood cells causes heart disease. It is likely, for example, that white blood cells multiply as a result of some other condition that is a risk for heart disease.

Find out more: Look at the heart section or women's health archive on USNews.com for more information on risk factors and how to help prevent heart disease.

Also, check out the National Women's Health Information Center's website on heart health.

Read the article: Margolis, K.L. et al. "Leukocyte Count as a Predictor of Cardiovascular Events and Mortality in Postmenopausal Women." Archives of Internal Medicine. March 14, 2005, Vol. 165, No. 5, pp. 500-508

Abstract online: http://archinte.ama-assn.org