Diabetes & The Body

Undiagnosed Kidney Disease

One in nine adult Americans has chronic kidney disease, but many don't know it and aren't taking steps to protect their damaged kidneys from getting worse.

New research by the National Kidney Foundation also says another 20 million Americans are at increased risk of getting kidney disease because they have diabetes, high blood pressure or other risk factors.

Those people need to get urine and blood tests from their doctors to see if they have kidney disease, according to the foundation's new guidelines.

It's "a silent disease" until the kidneys are severely damaged. If detected early and treated, kidney damage can be slowed, the panelists for the new guidelines said.

The goal is to slow the rate of kidney disease worsening so people can live a long time without needing dialysis or a kidney transplant.

The kidneys filter waste out of the bloodstream. With chronic kidney disease, the organs slowly lose that filtering ability, eventually becoming so damaged that patients die without dialysis or a kidney transplant.

Specialists have warned that end-stage kidney failure is increasing by 2 percent a year in the United States. Already, 300,000 Americans are on dialysis and 80,000 more are living with transplanted kidneys.

Until now, no one had a precise count of just how many people are living with earlier stages of chronic kidney disease, or how many were at increased risk of getting it. New government statistics allowed the National Kidney Foundation to do those counts.

Elderly people and people with diabetes, high blood pressure or a family history of kidney disease need tests for signs of impaired kidney function. The new guidelines recommend two tests:

1. People with kidney disease have increased protein in their urine. A simple urine test can be done either by a lab or in a doctor's office, using a special dipstick test that checks specifically for the protein albumin.
2. The second test estimates the patient's GFR _ glomerular filtration rate, a medical term for how well the kidneys are filtering. A blood test that measures levels of the metabolite creatinine allows doctors to estimate GFR.

There are four therapies to slow kidney damage:

1. Drugs called angiotensin II receptor blockers can slow kidney failure by about two years in people with advanced disease, and proponents expect they'll work even better if taken by people in earlier stages of chronic renal disease. They work by relaxing delicate blood vessels in the kidneys, and are similar to a type of blood pressure medicine called ACE inhibitors.
2. Strict blood pressure control is crucial.
3. In diabetics, strict blood sugar control protects the kidneys.
4. Low-protein diets often are recommended, although studies of their helpfulness are mixed.

To track how well therapy is working, patients need the blood and urine tests repeated at least yearly, and more often once the GFR drops below 60 _ a line separating mild disease from more serious organ damage.

The foundation is still studying how often screening should be offered to people who haven't tested positive for kidney disease yet. The American Diabetes Association recommends yearly urine tests for most diabetics. Doctors should not use regular dipstick tests - the kind often used for pregnant women - but the albumin-specific kind, or send the urine to a lab to be sure they detect small protein levels.