Saturday, Apr. 5, 2008; 4:00 AM
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FRIDAY, April 4 (HealthDay News) — Elevated levels of uric acid in the blood may be an early sign of diabetic kidney disease in people with type 1 diabetes, a new study suggests.

Researchers at the Joslin Diabetes Center in Boston noted that increased uric acid levels may appear before any significant change in urine albumin levels, the standard screening test for diabetic kidney disease.

In the study, the researchers checked serum uric acid concentration and urine albumin levels in 675 patients with type 1 diabetes. The results showed that 311 patients had microalbuminuria (small amounts of the protein albumin in the urine), an early sign of diabetic kidney disease. The other 364 patients had normal urine albumin levels.

While none of the patients had higher levels of albumin (albuminuria), one in five did have some impairment of kidney function.

“Our research showed that loss of kidney function takes place even in the absence of albuminuria in patients with type 1 diabetes,” study author Dr. Elizabeth T. Rosolowsky said in a prepared statement.

But she and her colleagues found that serum uric acid level was consistently related to kidney function. The higher the levels of uric acid in the blood, the lower the kidney function.

“The serum concentration of uric acid in these patients varied in a manner consistent with its having played a role in this early loss of kidney function,” Rosolowsky said.

The findings, published in the May issue of the Clinical Journal of the American Society of Nephrology, suggest that treatments to reduce uric acid may help slow the decline of kidney function in diabetes patients.

“Thus we have the hope of having a means to thwart the loss of kidney function while function is still a relatively preserved stage,” Rosolowsky said.

She noted that serum acid levels can be modified using drugs or by decreasing the amount of protein in a person’s diet.

“If follow-up studies, already under way, demonstrate that serum uric acid concentration predicts the course of early decline in kidney function, then clinical trials would be justified to test whether modifying serum uric acid concentration also modifies the course of renal function decline in type 1 diabetic patients with high normoalbuminuria or microalbuminuria,” Rosolowsky said.

Sometimes this filtering system breaks down. Diabetes can damage the kidneys and cause them to fail. Failing kidneys lose their ability to filter out waste products, resulting in kidney disease.

Why diabetes can cause kidney disease (nephropathy)

When our bodies digest the protein we eat, the process creates waste products. In the kidneys, millions of tiny blood vessels (capillaries) with even tinier holes in them act as filters. As blood flows through the blood vessels, small molecules such as waste products squeeze through the holes. These waste products become part of the urine. Useful substances, such as protein and red blood cells, are too big to pass through the holes in the filter and stay in the blood.

Diabetes can damage this system. High levels of blood sugar make the kidneys filter too much blood. All this extra work is hard on the filters. After many years, they start to leak. Useful protein is lost in the urine. Having small amounts of protein in the urine is called microalbuminuria. When kidney disease is diagnosed early, (during microalbuminuria), several treatments may keep kidney disease from getting worse. Having larger amounts is called macroalbuminuria. When kidney disease is caught later (during macroalbuminuria), end-stage renal disease, or ESRD, usually follows.

In time, the stress of overwork causes the kidneys to lose their filtering ability. Waste products then start to build up in the blood.

Finally, the kidneys fail. This failure, ESRD, is very serious. A person with ESRD needs to have a kidney transplant or to have the blood filtered by machine (dialysis).

Who gets kidney disease?

Not everyone with diabetes develops kidney disease. Factors that can influence kidney disease development include genetics, blood sugar control, and blood pressure.

The better a person keeps diabetes and blood pressure under control, the lower the chance of getting kidney disease.

Symptoms and diagnosis of kidney disease

The kidneys work hard to make up for the failing capillaries so kidney disease produces no symptoms until almost all function is gone. Also, the symptoms of kidney disease are not specific. The first symptom of kidney disease is often fluid buildup. Other symptoms of kidney disease include loss of sleep, poor appetite, upset stomach, weakness, and difficulty concentrating.

It is vital to see a doctor regularly. The doctor can check blood pressure, urine (for protein), blood (for waste products), and organs for other complications of diabetes.

Kidney Disease Prevention

Diabetic kidney disease can be prevented by keeping blood sugar in your target range. Research has shown that tight blood sugar control reduces the risk of microalbuminuria by one third. In people who already had microalbuminuria, the risk of progressing to macroalbuminuria was cut in half. Other studies have suggested that tight control can reverse microalbuminuria.

Treatments for kidney disease

Important treatments for kidney disease are tight control of blood glucose and blood pressure. Blood pressure has a dramatic effect on the rate at which the disease progresses. Even a mild rise in blood pressure can quickly make kidney disease worsen. Four ways to lower your blood pressure are losing weight, eating less salt, avoiding alcohol and tobacco, and getting regular exercise.

When these methods fail, certain medicines may be able to lower blood pressure. There are several kinds of blood pressure drugs. Not all are equally good for people with diabetes. Some raise blood sugar levels or mask some of the symptoms of low blood sugar. Doctors usually prefer people with diabetes to take blood pressure drugs called ACE inhibitors.

ACE inhibitors are recommended for most people with diabetes, high blood pressure, and kidney disease. Recent studies suggest that ACE inhibitors, which include captopril and enalapril, slow kidney disease in addition to lowering blood pressure. In fact, these drugs are helpful even in people who do not have high blood pressure.

Another treatment some doctors use with macroalbuminuria is a low-protein diet. Protein seems to increase how hard the kidneys must work. A low-protein diet can decrease protein loss in the urine and increase protein levels in the blood. Never start a low-protein diet without talking to your health care team.

Once kidneys fail, dialysis is necessary. The person must choose whether to continue with dialysis or to get a kidney transplant. This choice should be made as a team effort. The team should include the doctor and diabetes educator, a nephrologist (kidney doctor), a kidney transplant surgeon, a social worker, and a psychologist.

Kidney Transplantaion

Diabetes sometimes damages kidneys so badly that they no longer work. When kidneys fail, the person needs a way to replace their function, which is to clean the blood. One option is kidney transplantation.

Dialysis

Dialysis is a way of cleaning the blood with an artificial kidney. Dialysis is the more common form of kidney-replacement therapy. There are two types of dialysis: hemodialysis and peritoneal dialysis.

No matter which type is chosen, the person undergoing dialysis needs to work closely with the health care team to keep diabetes under control.

Hemodialysis
In hemodialysis, an artificial kidney removes waste from the blood. A surgeon must first create an “access,” a place where blood can easily be taken from the body and sent to the artificial kidney for cleaning. The access, usually in the forearm, can be made from the patient’s own blood vessels or from a piece of implanted tubing. The access is inside the body and cannot be seen from the outside. Usually, this surgery is done 2 to 3 months before dialysis starts so the body has time to heal.

Hemodialysis must be done 2 to 3 days per week, and lasts 3 to 5 hours each time. Blood travels through the artificial kidney, where waste products are filtered out, and the clean blood returns to the body. Only about 1/2 cup of blood is out of your body at any one time.

Usually, hemodialysis is done in a clinic, with many people receiving dialysis at the same time. Hemodialysis can also be done at home, but it requires a partner, such as a relative or friend, and special training.

Hemodialysis is not perfect for everyone. During treatments, people can have high or low blood pressure, an upset stomach or muscle cramps. A special diet is needed to stay healthy. Other problems can develop over time, such as nerve problems, anemia, bone disease, poor nutrition, problems with infection, problems with the access, and difficulty regulating insulin doses. Sometimes, these complications are the result of diabetes, not of hemodialysis.

Peritoneal dialysis
Another form of dialysis is called peritoneal dialysis. The lining inside your abdomen (the peritoneum) becomes the filter. A soft plastic tube is put into the abdomen by a surgeon. When the body heals, cleansing fluid (dialysate) is put into the abdomen through this tube. Waste products in the bloodstream pass through the peritoneum into the dialysate. Then the dialysate, along with the waste products is drained off.

The two main types of peritoneal dialysis are continuous ambulatory peritoneal dialysis (CAPD) and continuous cycling peritoneal dialysis (CCPD). People perform CAPD themselves by attaching a plastic bag filled with cleansing fluid to the tube in the abdomen and raising it to shoulder level. This causes the fluid to run into the abdomen. The bag is then unhooked or rolled up around the waist. In several hours, the fluid is drained out and thrown away. A fresh bag of fluid is then put into the abdomen to begin cleansing again. This is called an “exchange” and takes about 30-45 minutes. It is done 4 or 5 times a day. Between exchanges, the person can move around and perform daily activities.

In CCPD, a machine puts the cleansing fluid into the abdomen and drains it automatically. This is usually done at night during sleep.

CAPD and CCPD may be better treatments than hemodialysis for some people. With daily dialysis, the body does not build up too much fluid. This reduces the stress on the heart and blood vessels. A person is able to eat a more normal diet and have more time for work and travel.

Peritoneal dialysis is not for everyone, however. A person must be able to see well and do each step correctly to prevent infection in the abdomen. Anemia, bone disease, and poor nutrition can occur, just like in hemodialysis.

Your doctor will help you decide whether hemodialysis or peritoneal dialysis is right for you. Diabetes control remains important no matter which type of dialysis is chosen.