Millions are Unaware They Have Kidney Disease

With age, we hope, comes wisdom. Unfortunately, aging also brings us an increased risk for a number of serious health problems including cancer, heart disease and Alzheimer’s disease. We can also add another to the list – kidney disease – especially those of us who have high blood pressure or diabetes. And the risk increases even more if you are African American or Native American.

More than 20 million Americans have undetected moderate chronic kidney disease, according to the National Kidney Foundation, and another 20 million more are at risk. Despite that, the news is not entirely grim: “Most kidney disease can be prevented,” says Walter F. Piering, MD, “That’s very important. But if these patients are not diagnosed and treated, they will ultimately develop kidney failure.” Dr. Piering is a Professor of Medicine at the Medical College of Wisconsin and a specialist in nephrology, or the study of kidneys.

The two most common causes of kidney disease are diabetes and high blood pressure. Together they account for about two-thirds of all new cases. Kidney function can also be impaired by connective tissue disorders such as lupus erythematosus, by untreated infections of the urinary tract, or by streptococcus (“strep”) infections, especially in children. Most other causes are relatively uncommon. That includes kidney cancer, or nephroma, which represents less than 2% of all adult cancers. Kidney failure can also result from injury or poisoning, but these, too, are rare.

How Kidneys Work – and Fail
Kidney function is essential to health. Every day, our bodies use the food we consume for energy and self-repair. After the body has taken the nutrients it needs from the food, waste is sent into the blood. This waste also includes materials that the body generates from the normal breakdown of active tissues.

The kidneys – located near the middle of the back just below the rib cage – act as sophisticated filtering and reprocessing machines. Every day, these two fist-sized, bean-shaped organs process about 200 quarts of blood to sift out about two quarts of waste products and extra water. The waste and extra water become urine, which flows to the bladder through tubes called ureters. The bladder stores urine until it’s removed by urination. If the kidneys don’t remove these wastes, they build up in the blood and cause damage.

Detecting whether you have impaired kidney function is simple and inexpensive, Dr. Piering says: “All it takes are two simple tests – a blood pressure check and a urinalysis – and where we go wrong is, we don’t perform them often enough. I tell patients to insist on them every time they go to the doctor. In fact, the doctor doesn’t even have to perform them. A nurse or medical assistant usually does them. A lot of health fairs offer these tests, too.”

With a urinalysis, a patient simply collects a small quantity of urine in a cup, and the urine is quickly tested for the presence of protein. “That’s the hallmark test for kidney disease,” says Dr. Piering, whose patient emphasis is kidney transplantation and dialysis.

Kidney failure is also called end-stage renal disease (ESRD). Patients with ESRD must undergo dialysis or a kidney transplant in order to live. With dialysis, the patient’s blood is filtered by a special machine. Typically, the dialysis procedure takes three to four hours, and it must be repeated three or four times a week. Transplantation is surgery in which a donated kidney is used to replace a non-functioning one. Donated kidneys may come from an anonymous donor who has recently died or from a living person, usually a relative. The kidney must be a good match for the recipient’s body. The National Kidney Foundation says more than 70,000 patients are waiting for kidney transplants, but only about 11,000 will receive them this year because of a shortage of suitable organ donors.

How Diabetes and Hypertension Affect Kidneys
Diabetes is the leading cause of chronic kidney failure in the United States, accounting for 33% to 40% of new cases of chronic kidney failure each year. Persistent high blood sugar, the hallmark of diabetes, can damage the kidneys’ filtering mechanisms. Damaged kidneys can’t do a good job of cleaning out waste and extra fluids, so these build up in the blood instead of being excreted in urine.

Uncontrolled or poorly controlled high blood pressure is the second-leading cause of chronic kidney failure in the United States, accounting for 27% to 30% of all cases. Every year, high blood pressure causes more than 15,000 new cases of kidney failure in the United States. High blood pressure makes the heart work harder, which, over time, can damage blood vessels throughout the body. Blood vessel damage in the kidneys impairs the ability to remove extra fluids and waste; which raises blood pressure even more. A deadly cycle begins.

Preventing Kidney Disease
“You can control and prevent most kidney disease through good care,” Dr. Piering says. “If you have hypertension or diabetes, you’ve got to manage them.” New guidelines for preventing kidney disease impose stricter blood pressure levels than the traditional 140/90, he notes. “If you’ve been diagnosed with high blood pressure, you need to keep your readings at 135/85 or less. With diabetics, it’s 130/80.” And for people who have been diagnosed with reduced kidney function, the National Heart, Lung, and Blood Institute recommends they keep their blood pressure at 125/75 or lower.

It’s known that obesity is a risk factor for a number of conditions, including hypertension and diabetes. And because more children are becoming obese, they, too, should have their blood pressure and urine checked regularly for their risk of hypertension, diabetes and kidney dysfunction, Dr. Piering says.

How can you help to safeguard your health? Have your blood pressure and urine checked regularly. If you are at risk for kidney disease, diabetes or hypertension, work with your health provider to get on a program of diet and medication to prevent problems that threaten your health. “This is very important,” Dr. Piering says. “You can prevent kidney disease.”

Barbara Abel
HealthLink Contributing Writer

This article includes information from the National Kidney Foundation and the National Institutes of Health/National Institute of Diabetes & Digestive & Kidney Diseases and National Heart, Lung and Blood Institute.

MCW Health News presents up-to-date information on patient care and medical research by the physicians of the Medical College of Wisconsin.