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Protecting Your Kidneys

High blood pressure and diabetes are the biggest threats

SUNDAY, March 14, 2004 (HealthDayNews) -- You probably take your garbage disposal for granted and curse it when it fails.

Don't make the same mistake with your kidneys.

These fist-sized organs, which sit near the middle of the back, just below the rib cage, are charged with removing waste and excess water from the blood, and they do so by forming urine.

Kidneys are durable, but a variety of complications can keep them from doing their job. These include infections, stones, cancer and polycystic kidney disease, a genetic disorder in which multiple cysts grow in the organs. If these problems persist, the kidneys can fail, leaving patients unable to clean their blood.

But the leading causes of kidney failure in the United States are preventable -- high blood pressure and diabetes, says Dr. Brian Pereira, a professor of medicine at Tufts University School of Medicine in Boston and president of the National Kidney Foundation.

That's a message worth sharing in March, which has been designated National Kidney Month.

"There are probably about 20 million people with chronic kidney disease in the United States," says Pereira.

Diabetes accounts for 35 percent of all kidney failure in this country, while poorly controlled or uncontrolled high blood pressure is behind 23 percent of all U.S. cases, according to the kidney group.

High blood pressure hardens the vessels in the kidneys' filtering units, or glomeruli. Ultimately, unless the pressure is relieved, the kidney cells die off.

Diabetes damages the kidneys by allowing harmful amounts of blood sugar -- called glucose -- to reach the glomeruli.

Kidney disease is typically silent in its initial stages, Pereira says. "By the time you get symptomatic, it's pretty late," he says.

Many people can have chronic kidney disease for years without feeling ill. Only when the organs have all but failed do symptoms appear, among them upset stomach, perpetual fatigue, yellowed skin and swelling in the hands and feet.

That's why early detection of kidney disease is key, Pereira says. People can take steps to prevent the progression of kidney disease to kidney failure, but once failure occurs it can't be reversed.

About 80,000 people are diagnosed with kidney failure each year in the United States, according to the National Institutes of Health.

"Our mantra is that if you have a family history of diabetes, hypertension or kidney disease, or if you have diabetes or hypertension, you need to get your blood pressure checked and have your urine checked for protein and your blood checked for creatinine," Pereira says. Protein in the urine and elevated creatinine in the blood are signs of kidney damage.

Once the kidneys fail, patients must have their blood cleaned mechanically, through a process called dialysis. At any given time, some 325,000 Americans are on kidney dialysis, Pereira says. Dialysis comes in two forms: hemodialysis, in which patients go three times a week to a clinic for several hours, and peritoneal dialysis, which can be done at home overnight.

Dialysis patients have two options: undergo a kidney transplant or spend the rest of a potentially abbreviated life being dialyzed. Last year, surgeons performed 23,373 kidney transplants in the United States, according to the United Network for Organ Sharing. Currently, about 60,000 people are signed up to receive a donor kidney.

Although kidney transplants are lifesaving, they're far from fail safe. New drugs to suppress the immune system have driven down rejection rates for kidney grafts -- 10 percent vs. 30 percent a decade ago -- but transplant failure remains a significant hurdle for patients. Organ failure is now the fourth-leading cause of end-stage kidney disease in this country, health officials say.

Just as people with healthy kidneys can take steps to keep them that way, those on dialysis can do things to prevent worsening of their organ damage.

"If you're on dialysis, diet is one of the most important things for you. It can help control the buildup of toxins that could" exacerbate kidney damage, says Elaine Drees, a nurse and nutritionist at Gambro Healthcare in Tucson, Ariz., which treats dialysis patients.

Two key nutrients for kidney patients to watch are potassium and phosphorous. A spike in potassium can be lethal to the heart, while poorly controlled phosphorous can lead to bone disease and hardening of the blood vessels, Drees says.

To control potassium, Drees advises avoiding foods rich in the nutrient, such as bananas, potatoes and tomatoes, in favor of lower-potassium fruits and vegetables like apples, grapes, pineapples and plums. Phosphorous can be kept in check with medication.

Kidney dialysis patients also need to load up on protein, says Drees, who chairs the patient and public education committee of the National Kidney Foundation's council on renal nutrition. They typically require 20 percent more high quality animal protein -- six to eight ounces a day -- than people not on dialysis.

Periera says scientists are working on drugs that can do the job -- at least partially -- of dialysis machines. But these are "nowhere near" being ready for patients. In the meantime, dialysis will continue to be an obtrusive, if lifesaving, technology.

"I like to think of it [dialysis] as, yes it's an intrusion, but it frees patients up for the rest of their life," Drees says. "They can work, be with their family."

More information

Visit the National Kidney Foundation and the National Library of Medicine for more on kidney health.

SOURCES: Brian Pereira, M.D., professor, medicine, Tufts University School of Medicine, Boston, and president, National Kidney Foundation; Elaine Drees, M.S., R.D., nurse and nutritionist, Gambro Healthcare, Tucson, Ariz., and chairwoman, patient and public education committee, National Kidney Foundation's council on renal nutrition
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