Scientists have identified three biological markers, all found in the blood, that can help predict a person's risk of developing chronic kidney disease.
People with elevated levels of two of these markers were 2.4 times more likely to develop chronic kidney disease nine and a half years later than those with normal levels. And those with elevated levels of all three markers were 3.4 times more likely to develop high levels of protein in the urine, a condition known as macroalbuminuria, which is a sign of worsening kidney function.
These markers could be used along with known risk factors for chronic kidney disease, such as high blood pressure and diabetes , to improve doctors' ability to predict who will develop this condition. They might also help researchers better understand how the disease develops, the researchers said.
However, the authors note, the study included only people of European ancestry, and work on more diverse populations is needed to confirm the findings.
In chronic kidney disease, the kidneys gradually lose their ability to do their job, that is, to remove waste and excess water from the body. About 13 percent of adults in the United States, or 26 million people, suffer from the condition, according to the National Institutes of Health.
Currently, doctors assess kidney function by looking at levels of the compound creatinine in the blood. If the kidneys aren't working properly, creatinine may accumulate. But blood tests for creatinine levels appear abnormal only after the kidneys have already lost a lot of their function, said study researcher Dr. Caroline Fox, of the National Heart, Lung, and Blood Institute's Framingham Heart Study, in Framingham, Mass.
To look for more disease markers, Fox and her colleagues examined blood samples from 2,300 individuals. The samples were collected between 1995 and1998 as part of another study. Between 2005 and 2008, the participants had their kidney function checked. By this time, 9 percent had developed chronic kidney disease, and 8 percent had macroalbuminuria.
In the blood samples taken at the study's start, the researchers found elevated levels of two markers associated with the later development of chronic kidney disease. These were homocysteine, a molecule that builds proteins and is also associated with cardiovascular disease , and aldosterone, a hormone that affects the way the kidneys handle salt. Both of these markers, along with a protein that indicates damage to the heart called B-type natriuretic peptide, were associated with macroalbuminuria.
It's possible that reducing levels of homocysteine, or interfering with the processes that involve the other markers, may decrease the risk of chronic kidney disease, the researchers say. However, more research needs to be done confirm this.
The study was published online today (Oct. 21) in the Journal of the American Society of Nephrology, andwas funded by the National Heart, Lung, and Blood Institute.