For Kidney Disease, Some Tests are More Important than Others

New York, NY
June 8, 2006

( New York, NY) – When it comes to diagnosing and determining the best course of treatment for kidney disease, one all-too-often-neglected test appears to stand above all the others, according to a new report in the New England Journal of Medicine.

In the report, a group of internationally-recognized experts led by Dr. Lesley Stevens of Tufts-New England Medical Center conclude that measuring glomerular filtration rate, or GFR, is the most accurate way to diagnose kidney disease. GFR is also the best tool to gage a patient's stage of disease, enabling doctors to plot out the most appropriate course of treatment.

In other words, knowing your GFR can save your life.

"Everyone who is at risk of kidney disease must get their GFR checked on a regular basis," says Joseph Vassalotti, MD, Chief Medical Officer at the National Kidney Foundation. "It's a relatively easy test to perform and understand. And for the millions of people at risk of kidney disease, it could make the difference between life and death."

By now, most people know to ask their doctors to test their blood pressure and cholesterol. But too few know to ask about their GFR, a measure of how effectively your kidneys are removing wastes and excess fluid from the blood. A low GFR -- less than 60 -- means a patient has developed kidney disease, which currently affects more than 20 million Americans, or 1 in 9 adults. The National Kidney Foundation estimates that another 20 million Americans are at increased risk of the disease, and most have no idea.

To calculate GFR, doctors draw blood and measure levels of creatinine, then simply plug that value into an equation that incorporates a patient's age, race, and gender. Even though calculating a patient's GFR is a relatively easy task, it's something that many physicians do not do -- even for patients with diabetes, high blood pressure, and other risk factors for kidney disease.

In the report, experts describe the strengths and weaknesses of various techniques to estimate GFR, and the best way to use the value when treating chronic kidney disease, or CKD. Although they conclude that GFR is the best way to measure kidney function, they note that estimates of GFR can be less accurate in people with unusual body changes, such as muscle wasting, which can affect levels of creatinine. GFR is also less useful in people with rapidly changing kidney function, and in those without CKD, whose GFRs are still relatively high.

"Too many physicians do not routinely track GFR in people at risk of CKD," says Dr. Vassalotti. "This means that, unfortunately, it's often up to you, the patient, to know what your GFR is, and what that value means. Your kidneys will thank you for it."

The National Kidney Foundation is dedicated to preventing kidney and urinary tract diseases, improving the health and well being of individuals and families affected by these diseases, influencing public policy in support of the kidney community and increasing the availability of all organs for transplantation. For more information, visit www.kidney.org.