In February 2005, Rita Miller, a party organizer in Chesapeake, Va., felt exhausted from what she thought was the flu. She was stunned to learn that persistent high blood pressure had caused such severe kidney damage that her body could no longer filter waste products from her blood.

"The doctor walked over to my bed and said, 'You have kidney failure – your kidneys are like dried-up peas,' " recalled Miller, now 65, who had not been to a doctor or had her blood pressure checked for years.

"The doctor said, 'Get your family here right away,' " she said. "They were telling me I might not make it. I was in shock. I started dialysis the next day."

Miller was one of the millions of Americans unaware that they are suffering from chronic kidney disease, which is caused in most cases by uncontrolled hypertension (as in her case) or diabetes, and is often asymptomatic until its later stages.

The number of people with the disease has been rising at a significant pace, thanks in large part to increased obesity and the aging of the population.

An analysis of federal health data published in November 2007 in the Journal of the American Medical Association found that 13 percent of American adults – about 26 million people – have chronic kidney disease, up from 10 percent, or about 20 million people, a decade earlier.

"We've had a marked increase in chronic kidney disease in the last 10 years, and that continues with the baby boomers coming into retirement age," said Dr. Frederick J. Kaskel, director of pediatric nephrology at the Children's Hospital at Montefiore in the Bronx, N.Y. "The burden on the health care system is enormous, and it's going to get worse. We won't have enough units to dialyze these patients."

Concerned about the emerging picture, federal health officials have started pilot programs to bolster public awareness, increase epidemiologic surveillance and expand efforts to screen those most at risk – people with high blood pressure, diabetes or a family history of kidney disease.

Those people, and those who already have the disease, can often be helped by the same kinds of medicine and lifestyle changes used in hypertension and diabetes. They are urged to quit smoking, lose weight, exercise regularly, restrict their diets and, if necessary, control their blood pressure and diabetes with medication. But such efforts cannot restore kidney function that has been lost.

The trouble is that most people know very little about chronic kidney disease and rarely ask their doctors about kidney function.

And many of those who have it feel relatively well until late in the illness, although they may experience nonspecific symptoms like muscle cramps, loss of energy and poor concentration.

"When most people think of kidney disease, they think of dialysis or transplantation," said Dr. Joseph A. Vassalotti, chief medical officer for the National Kidney Foundation, a major education and advocacy group. "They don't understand that it encompasses a spectrum, and that the majority of patients are unaware they have the condition."

Chronic kidney disease progresses over the course of years, with its phases determined according to two criteria: the presence of protein in the urine and how effectively the kidneys are processing waste products.

Patients get dialysis or a kidney transplant only when they are in the final stage of the disease, also known as kidney failure or end-stage renal disease. But the path to kidney failure can take years.

"Only a tiny percentage of patients with kidney disease need dialysis," said Dr. Stephen Fadem, a Houston nephrologist and vice president of the American Association of Kidney Patients.

Chronic kidney disease itself can damage the cardiovascular system and lead to other serious medical conditions, like anemia, vitamin D deficiencies and bone disorders. Patients are far more likely to die from heart disease than kidney failure.

Because African Americans, Latinos and other minority communities suffer disproportionately from hypertension and diabetes, they experience higher rates of kidney disease.

In 2005, more than 485,000 people were living on dialysis or with a transplant, at a total cost of $32 billion. Kidney treatment accounts for more than a quarter of Medicare's annual expenditures.

The National Kidney Foundation, which has worked closely with the Centers for Disease Control and the National Institutes of Health on initiatives related to chronic kidney disease, has focused on education and screening, particularly in minority communities.

Terri Smith, the urban outreach director at the foundation's Connecticut affiliate, says she spends a lot of her time going to churches and community centers to talk about kidney disease, and has been surprised that so few people know anything about it.

"They're very aware of hypertension and diabetes, but it was a revelation to me that people didn't get the connection to kidney disease," she said. "People have no idea they should eat less than a teaspoon of salt a day. I teach them how to read labels; I give them questions they should be asking the doctor."

In Michigan, the local NKF affiliate reaches out to hair stylists and other salon workers in minority communities, training them in talking to their clients about getting screened.

Several years ago, after Mary Hawkins, 61, a nurse who lives in Grand Rapids, Mich., received a warning about kidney disease from a masseuse at her local salon, she made an appointment to see her doctor.

She learned that her blood pressure was high. Now she takes three medications to keep it under control, exercises three times a week, takes tai chi classes, no longer smokes and attends a dance class at the same salon.

"I knew kidney disease existed, but I wasn't in tune with the risk," she said. "You get so caught up in your own life that the last thing you think about is your health – even though it should be the first thing."