Blood Protein Disparity May Help Explain Blacks' Increased Heart Risk

Higher levels of the key blood protein albumin might help explain why blacks are at elevated heart risk compared to whites, a new study suggests.

Elevated levels of albumin in urine-based tests are tied to an increased risk of coronary heart disease in black Americans but not whites, the study found.

Rising albumin levels in urine samples are a sign of kidney damage and a strong risk factor for heart disease, said lead researcher Dr. Orlando Gutierrez of the University of Alabama at Birmingham.

Blacks tend to have higher levels of albumin in their urine than whites, which "may contribute to racial disparities in cardiovascular outcomes," according to background information in the study.

Gutierrez's team examined data from more than 28,000 black and white adults aged 45 and older. Over a median (midpoint) four and a half years of follow-up, there were 616 heart disease events, including 421 nonfatal heart attacks, among the participants.

Blacks with the highest urinary albumin levels were about 50 percent more likely to suffer a coronary event than whites, according to the study, which was published in the Aug. 21 issue of the Journal of the American Medical Association.

Gutierrez's team said the findings confirm prior studies pointing to urinary albumin as an important signal for heart disease risk in the general population. In addition, the study is the first to show that this risk differs by race.

Future studies should examine whether measuring urinary albumin levels can improve the diagnosis and management of heart disease in blacks, they said.

One expert said the study reinforces the link between kidney dysfunction and heart trouble.

"Just as diabetes, hypertension and tobacco use are well-known strong risk factors leading to heart attack, vascular disease and stroke, there has been more evidence to suggest that chronic kidney disease is being recognized as another coronary disease risk marker," said Dr. David Friedman, chief of heart failure services at North Shore-LIJ's Franklin Hospital in Valley Stream, N.Y.

"Possibly on the basis of microvascular disease, these researchers are linking higher levels of ... albumin, which, if found in the urine, is not only an indirect measure of kidney injury, but now is associated with higher rates of heart attacks, perhaps more so in black than white study participants," he said.

Friedman said the new study suggests that urine albumin tests might help spot people at heart disease risk, "much like we use pre-diabetes or pre-hypertension as risk predictors. In this way, we could better target our strategies to try to help predict and better treat heart disease before it happens in certain higher-risk populations."

More information

The U.S. National Heart, Lung, and Blood Institute has more about coronary heart disease.