Excess Protein in Urine Is Indicator of Heart Disease Risk in Whites, but Not Blacks, Study Suggests

The cardiovascular risk that is associated with proteinuria, or high levels of protein in the urine, a common test used by doctors as an indicator of increased risk for progressive kidney disease, heart attack and stroke, has race-dependent effects, according to a new study by researchers at Wake Forest University School of Medicine.

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“Proteinuria, a long accepted indicator of heart disease risk, has far less impact on blacks than it does on whites,” said Barry Freedman, M.D., John H. Felts III Professor, chief of the Section on Nephrology, and lead researcher on the study. “In the medical community, it is believed that the more protein in a patient’s urine, the greater the risk for heart disease and stroke, and this is true–in white populations. Our study indicates that excess protein in the urine–a common finding with progressive kidney disease in individuals with diabetes–is strongly associated with calcium deposition in the major arteries in white patients, but not in black patients. Therefore, proteinuria appears to be associated with an increased risk of heart attack in the white ethnic group. There may be biologic factors predisposing whites to heart disease or protecting blacks from developing it.”

In the general community, blacks have more heart disease risk factors than whites, including higher blood pressures and LDL (known as “bad”) cholesterol levels, and higher blood sugars in patients with diabetes, Freedman explained. As such, they face a higher risk for heart attack than whites, he said.

However, several large studies have shown that despite having more risk factors for hardening of the arteries, black men had less calcium in the heart arteries–one-eighth the amount–compared to white men. In addition, given access to equivalent healthcare as whites, blacks with diabetes face only half the risk of a heart attack, indicating that blacks appear to somehow be protected from the cardiovascular effects of these risk factors, Freedman said.

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