Obesity May Affect Kidneys Differently in Whites, Blacks

New York, NY (March 1, 2010) — Obese African-Americans may be more vulnerable to the effects of chronic kidney disease than obese whites, new findings from the National Kidney Foundation's Kidney Early Evaluation Program (KEEP) show.

KEEP is a free, community-based program that has screened more than 140,000 people across the U.S. at high risk for chronic kidney disease since its launch in 2000. In the new study, Dr. Andrew S. Bomback of Columbia University Medical Center in New York City and his colleagues looked at 37,107 obese KEEP participants (52 percent white, 48 percent black) to investigate whether there might be ethnic differences in how obesity affected kidney function. The study appears in the March issue of the American Journal of Kidney Diseases, the official journal of the National Kidney Foundation.

While whites were more likely than African Americans to have components of the metabolic syndrome—a group of heart disease risk factors including high blood pressure, high cholesterol, and high blood glucose—black individuals were more likely to show signs of failure in kidney hormone function, Dr. Bomback and his team report.

And while the kidneys of obese whites were more likely than those of obese blacks to show severe impairment in blood filtering capacity, blacks were more likely than whites to be excreting abnormal amounts of protein in their urine, which is a sign of ongoing kidney damage and increased cardiovascular risk.

Dr. Bomback and his colleagues also found that among people with more advanced kidney disease, blacks were more likely than whites to have anemia and excessive secretion of parathyroid hormone, which is responsible for regulating levels of calcium in the body.

The findings might help explain why blacks and whites with chronic kidney disease have different long-term outcomes, Dr. Bomback and his colleagues say.

Individuals are considered to be at high risk for chronic kidney disease if they have diabetes or hypertension, or they have a close relative with diabetes, hypertension, or kidney disease. Many people with chronic kidney disease aren't aware of it, notes Dr. Peter McCullough, vice chair of KEEP; he points out that about a quarter of the people identified as having kidney disease through KEEP were "completely unaware" that they had any kidney problems. "The majority of chronic kidney patients diagnosed through KEEP have not seen a nephrologist, suggesting that their own primary care physicians may be unaware of it," he adds.

The National Kidney Foundation holds KEEP screenings in cities across the U.S. for those at risk. To find a local screening or to learn more about chronic kidney disease, risk factors, or treatments, contact the National Kidney Foundation at www.kidney.org or (800)622-9010.