Researchers have found that reduced kidney function, even in healthy individuals with no other risk factors, appears to increase the risk of cardiovascular disease. Their paper, “Cardiovascular Effects of Unilateral Nephrectomy in Living Kidney Donors,” was published in the journal of the American Heart Association, Hypertension.

Although an increased risk for heart disease has been observed in people with chronic kidney disease, the direct effect of diminished kidney function on the heart has been difficult to prove, since these patients present other risk factors as well.

Researchers wanted to investigate if this direct link could be established. If the correlation proves true, kidney disease could present a public health concern, since mild chronic kidney disease is fairly common, affecting over 10 percent of the U.S. population.

The team examined 68 kidney donors, a group characterized by extremely good health, to see if the decrease in kidney function known to follow donation had a negative influence on their cardiac and vascular systems. The scientists compared the group with 56 controls through the first year after surgery, and found that the kidney donors had an expected decline in kidney function, as measured by the glomerular filtration rate (GFR) and the levels of albumin in the urine. Moreover, the researchers observed increases in the mass of the left ventricular, a predictor of heart disease risk, and in measures of heart damage, such as cardiac troponins, a protein that is a marker for heart muscle damage. Such results indicate that a reduction in kidney function can lead directly to harmful changes in the heart and blood vessels, even without the presence of other risk factors.

In light of these results, researchers suggest that heart disease risk be a central topic when doctors discuss kidney malfunctions with patients. The researchers also stressed that kidney donors should not worry. As senior author Jonathan Townend, MD, professor of cardiology at the Queen Elizabeth Hospital Birmingham, said in a press release, “Kidney donors are already highly selected as healthy individuals. Our paper has shown that kidney donation causes very small adverse effects on the heart and blood vessels that took careful and accurate measurements to detect. We do not yet know if these effects are maintained over the long term. Even if there is a small increase in your long-term risk of heart disease after donation, it is still likely that you will be at lower than average risk.”