From 1994 to now, the number of people with kidney disease has risen by 3 percent -- from an estimated 20 million people to as many as 26 million people, report researchers at Johns Hopkins University in Baltimore, Tufts-New England Medical Center in Boston and Cleveland Clinic Foundation. Their findings are published in the Journal of the American Medical Association.

Kidney disease can lead to kidney failure. It heightens the risk of heart attack, stroke, high blood pressure and premature death. It causes anemia, bone disease and malnutrition.

In 2005, at least 107,000 Americans learned they had kidney failure. That year, more than 485,000 had dialysis or a kidney transplant, costing $32 billion, according to the National Institutes of Health's US Renal Data System. By 2020, nearly 785,000 people will be receiving treatment for kidney failure, costing $53.6 billion, the agency predicts.

Contributing Factors

The alarming trend is attributable in part to increases in the incidence of diabetes, high blood pressure, obesity and aging, according to Paul W. Eggers, PhD, director of kidney disease epidemiology at the National Institute of Diabetes and Digestive and Kidney Diseases. Still, those factors don't fully explain the upsurge in cases.

The researchers crunched data gathered on 28,000 adults through interviews, exams and lab tests conducted by the National Center for Health Statistics during a span beginning in 1988 and ending in 2004.

They considered creatinine levels in blood samples, adjusting for age, gender and race, which were known to affect results. Creatinine is a waste product produced when muscle cells break down during activity. When kidneys aren't functioning properly, creatinine levels may rise. They also checked urine samples for albumin, a protein that may leak from the blood to the urine when kidneys are damaged.

Silent Killer

The vast majority of people with kidney disease are unaware of it until they reach the final stage of the disease -- Stage 5, or kidney failure. The latest research found that fewer than 23 percent of people with Stage 3 kidney disease were aware of the problem. Only 42 percent of those individuals who had Stage 4 kidney disease knew about it.

"Kidney disease is often silent until late stages, but if we can find it early we can do a lot to prevent kidney failure," explained Andrew S. Narva, MD, FACP, director of the NIH's National Kidney Disease Education Program.

"If you have diabetes, high blood pressure or a family history of kidney problems, you are at risk and should be screened for kidney damage with routine blood and urine tests," he advised.

"To help protect the kidneys' small blood vessels, carefully control high blood pressure, and blood sugar if you're diabetic," Narva continued, "and ask your doctor if you should take an angiotensin converting enzyme inhibitor or angiotensin receptor blocker."

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