A healthy dose of kidney data: GFR

12:08 pm | 86°
August 26, 2008 |
Arizona Living

A healthy dose of kidney data: GFR

by Mary Beth Faller - Aug. 26, 2008 12:00 AM
The Arizona Republic

Many adults know their cholesterol score, and how important it is to manage.

The Arizona Kidney Foundation is launching a campaign to get people to know their GFR - or glomerular filtration rate, a measure of how well their kidneys are functioning - the same way they know their cholesterol. The "Know Your GFR" campaign will include 30-second TV spots that will begin airing this week.

"In the U.S. right now, 26 million Americans are suffering from some stage of chronic kidney disease. Only one in 10 of those know they have it. It's really a silent disease," says Jeffrey D. Neff, chief executive officer of the Arizona Kidney Foundation. More than 390,000 Arizonans have kidney disease, about the same rate as the U.S. In its early stages, the disease has no symptoms.

People at an increased risk are those with diabetes, high blood pressure, heart disease and a family history. Blacks, Native Americans and Hispanics also are more likely to have the condition. The rate is increasing, due mostly to the increasing incidence of diabetes and hypertension.

Kidney disease is incurable, but with early detection, progression can be slowed considerably, says Savas Petrides, a Phoenix nephrologist, or kidney specialist.

The kidneys have about half a million filter units, or glomeruli, he says. Blood flows in and is passed through like a sieve, and waste is excreted through urine.

The GFR is a measure of how much blood is being filtered per minute. In a normal kidney, about 85 to 125 cubic centimeters of blood is filtered through the glomeruli every minute, so an average score is 100; Petrides usually expresses the score as a percentage.

"If it gets under 60, you start to have secondary complications such as anemia or bone disease," Petrides says. "If it gets under 20 percent, that's the time at which things are going to start deteriorating quicker and we need to intervene. They go on the list for a transplant."

Patients with a score of 10 to 15 would need to go on dialysis, a procedure in which the blood is mechanically filtered at a dialysis center.

In diabetics, the kidneys' filters become scarred, forcing the rest of the kidneys to work harder. Diabetics usually must begin dialysis when their GFR reaches 15, while people without diabetes start dialysis when their score is around 10, he says.

"If you find someone is at 50 or 60, they are nowhere near needing dialysis. If they modify their health care and lifestyle, they'll never get to 10 or 15," Petrides says.

"If you get your cholesterol score and it's 220, you know that's not the goal. No one knows about GFR. Your GFR could be 50 and you feel fine."

Treatment of chronic kidney disease has progressed over the years, he says.

"Seven years ago, from the time we first saw a patient to when they went on dialysis was about a year," says Petrides, a partner in the Arizona Kidney Disease and Hypertension Center. "Now, from the first visit to the start of dialysis is almost three years."

Patients now have frequent visits to manage their anemia, blood pressure and diabetes, and they undergo nutritional and lifestyle counseling, called a chronic kidney disease (CKD) program.

"If they get into a CKD program early, they may never wind up on dialysis before something else gets them," he says.

Previously, labs used to measure only the creatine in a person's blood, but the score was not as precise as GFR. After lobbying by nephrologists, most commercial labs calculate the GFR on the basic lab test, which is done during a routine physical and is covered by insurance.

The Arizona Kidney Foundation's GFR campaign will later shift to educating primary-care doctors on importance of checking the GFR and discussing the results with patients.

For more information, visit azkidney.org.

http://www.azcentral.com/arizonarepublic/arizonaliving/articles/2008/08/26/20080826kidney0826.html