Urine Test Predicts Heart Problems in Postmenopausal Women

FOR RELEASE: 4 p.m. EDT, MondayJune 25, 2001

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American Heart Association journal report:Urine test predicts heart problems in postmenopausal women

DALLAS, June 26 -- A routine test can measure levels of a protein in urine samples and may reveal early, symptomless cardiovascular disease in postmenopausal women, researchers report in today's Circulation: Journal of the American Heart Association.

Dutch scientists measured levels of albumin, a common protein in the blood, in urine samples from 1,118 healthy postmenopausal women who were followed for up to 18 years. Women in the highest quintile of urinary albumin levels had an age-adjusted cardiovascular death rate 4.4 times that of women without detectable albumin in their urine. Albumin levels are obtained by a urinalysis that is part of a routine medical exam.

"We suggest that urinary albumin is an independent risk factor for cardiovascular mortality in this large group of postmenopausal women," says Jan Dirk Banga, M.D., Ph.D., a co-author of the report.

A small amount of albumin in the urine (microalbuminuria) indicates that blood vessels in the kidneys are leaking, says Banga, who is a consultant in vascular medicine at the University Medical Center in Utrecht, The Netherlands. Scientists believe that this leakage results from malfunctioning endothelial cells, which line the inside of blood vessels.

"The endothelial cells may already be damaged and malfunctioning at the early stage of heart disease when there are no symptoms. Our finding supports the hypothesis that albumin in the urine is a reflection of vascular damage and a marker of early disease," he says.

Among people with diabetes and high blood pressure, microalbuminuria is linked to an increased risk of developing kidney damage or heart disease.

Smoking, high cholesterol and hypertension are among the well-documented risk factors for heart disease. The known hazards, however, do not give a full picture of a person's heart danger, says Banga. He and his colleagues have been looking for additional markers that would provide better risk estimation."A routine urinary analysis will never be able to predict cardiac death in an individual, but it may predict an increased risk," Banga says.

The women studied were among 12,239 volunteers who donated a urine sample between 1976 and 1978 while participating in an experimental breast-cancer screening study. When the women provided a sample -- each of which was frozen and stored -- they also granted permission for its use in future scientific studies.

The researchers ran albumin analyses of 549 women in the cancer study who died of cardiovascular disease and a control group of 569 women who did not. The women were divided into five groups, or quintiles, based on the amount of the protein present in their urine.

Women in the group with the highest urine albumin levels had a cardiovascular death rate of 13.2 for each 1,000 years of the study's follow-up (a woman followed for 15 years was counted as 15 follow-up years). This number compared to 2.6 deaths per 1,000 follow-up years among the women in whom urinary albumin could not be detected.

To determine the relative importance of microalbuminuria as a risk indicator, researchers calculated death rate ratios for each quintile of albumin levels. The women in the highest quintile of albumin loss had a 4.4 times greater risk of cardiovascular death compared to women without microalbuminuria.

The new finding does not necessarily apply to males and premenopausal women because neither group was represented in the study, says Banga. Larger studies will be needed to determine if their finding applies to other populations.

Several important questions remain to be answered in future studies, he says. Some issues to address would be treatment of microalbuminuria and determining whether lowering albumin in the urine would reduce the risk of cardiovascular death. Banga also says further research into the mechanism that links microalbuminuria to increased cardiovascular risk is needed.

"We know from studying people with diabetes that we can reduce microalbuminuria with ACE inhibitors and that this may help protect them," Banga says. "We also know that if we lower high blood pressure, we can reduce the degree of microalbuminuria and reduce cardiovascular risk. Therefore, the treatment of microalbuminuria looks promising for other types of patients."

Co-authors are Mark Roest, Ph.D.; Wilbert M. T. Janssen, M.D., Ph.D.; Diederick E. Grobbee, M.D., Ph.D.; Jan J. Sixma, M.D., Ph.D.; Paul E. de Jong, M.D., Ph.D.; Dick de Zeeuw, M.D., Ph.D.; and Yvonne T. van der Schouw, Ph.D.

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NR01-1304 (Circ/Banga)

Media Alert: Dr. Banga can be reached by phone at 011-31-30-250-7399, by fax at 011-31-30-251-8328, and by e-mail at [email protected]. (Please do not publish contact information.)