Diabetic nephropathy

Definition

Diabetic nephropathy is kidney disease that occurs because of diabetes and can lead to chronic kidney failure and end-stage kidney disease.

Description

Nephropathy means kidney disease or kidney damage. Diabetic nephropathy is kidney disease or kidney damage that occurs because of diabetes. Diabetes puts a lot of strain on the kidneys, which over time can lead to significant kidney damage. Diabetic nephropathy generally causes no noticeable symptoms until it is very progressed, which means that it is extremely important for individuals with diabetes to be regularly screened for kidney damage. When the disease is caught at the very early stages it can be slowed, and in some cases the damage can even be reversed.

Demographics

About 40 out of every 100 individuals with diabetes will eventually develop diabetic nephropathy. Individuals who smoke, have high blood pressure , or who do not strictly control their blood sugar levels are more likely to get kidney diseases. Individuals who have high cholesterol are also at increased risk. Certain groups are more likely to get diabetic nephropathy. These include individuals of Native America, African American, and Hispanic descent.

Causes and symptoms

Every individual has two kidneys, each about the size of a fist. Their primary job is to filter the blood and remove waste products. The kidneys generally filter 200 quarts of blood every day, during which they remove about two quarts of waste and extra water. This waste and extra water is removed from the body as urine.

Each kidney contains about a million nephrons that perform the filtering function of the kidney. In each nephron there is a glomerulus, which is a twisted mass in which the waste products and extra water of blood is filtered out to become urine. The glomerulus contains many tiny openings through which small waste molecules can pass. Larger red blood cells and protein are too big to get through the holes. Over time the excess blood sugar that occurs during diabetes damages the glomerulus. This causes the holes to tear and protein to able to slip through, or leak, from the glomerulus. It is in this way that protein becomes present in the urine. Over time the damage to the kidneys continues and they are no longer able to do their job and filter waste from the blood stream.

In its early stages diabetic kidney disease has no symptoms. Therefore it is extremely important for individuals with diabetes to have their urine tested for protein on a regular basis, protein in the urine is often the first sign of the disease. Symptoms of later stages of diabetic kidney disease can include fluid build up, fatigue, headache, itching , nausea, poor appetite, swelling in the legs or around the eyes, and urine having a foamy or frothy appearance.

Diagnosis

Diabetic kidney disease is usually first diagnosed by a urine protein test. Normal urine does not contain any protein. Protein in the urine is a sign of damage to the kidneys. The first urine test is called a microalbuminuria test. It is an extremely sensitive laboratory test that can measure even very small amounts of protein in the urine. This test can detect kidney damage very early, often long before any symptoms occur. In some cases a biopsy may be done on the kidney to look for signs of damage to confirm the diagnosis. In many cases where diabetes has been present for many years this is not considered necessary to make the diagnosis.

Treatment

The treatment for diabetic kidney disease attempts to halt or slow the progress of the disease. Treatment usually includes strict control of blood sugar. Reducing blood pressure is very important to treating diabetic kidney disease because high blood pressure puts strain on the kidneys and can speed the progress of the disease. Individuals are advised to stop smoking , eat a diet low in sodium , not drink alcohol, and exercise regularly. In many cases this may be enough to control blood pressure. If it is not the doctor may prescribe medication to help lower the individual's blood pressure. The doctor may also prescribe medicine to help lower the individual's cholesterol level if it is not successfully lowered through changes in diet and exercise.

Diabetic nephropathy often advances to endstage kidney disease. It can take 10 to 20 years or longer to reach this stage. End-stage kidney disease occurs when the kidney is functioning at less than 10% of normal levels. When this occurs the kidney cannot filter out enough waste products and extra water to keep the individual healthy. If the waste products are not filtered they build up in the system and be fatal. The waste products and extra fluid can be filtered manually, through dialysis, or can be filtered through a working kidney after a kidney transplant.

QUESTIONS TO ASK YOUR DOCTOR

• How far progressed is my diabetic nephropathy?
• What steps can I take to reduce the risk of my nephropathy becoming more severe?
• How often should I have my urine protein level checked?

Nutrition/Dietetic concerns

Individuals with diabetic kidney disease should carefully monitor the food they eat. The diet should contain only small amounts of protein because excessive protein puts even more of a strain on the kidneys. Salt intake should be very low because salt can increase blood pressure. When kidney disease progresses to the point at which little or no urine is being produced fluid intake must be monitored carefully so that fluid does not build up in the system.

Therapy

Nutritional therapy can be helpful for individuals with diabetic kidney disease. A healthy diet that is low in fat and protein can help keep the disease from worsening. A nutritionist can work with the individual to develop a healthy eating plan that will best keep blood sugar levels under control, reduce blood pressure, and reduce cholesterol. Physical therapy may be appropriate for individuals who are unable to exercise comfortably to help them develop a safe, healthy exercise routine to improve blood pressure and cholesterol levels.

Prognosis

There is some evidence that very early stage diabetic nephropathy can be reversed with careful control of blood sugar. Once nephropathy has passed the microaluminuria stage the focus is on slowing the progression of the disease. Typically, the disease continues to slowly worsen over time becoming chronic kidney failure, and eventually end-stage kidney disease. When end-stage kidney disease occurs the patient must either have regular dialysis treatments or a kidney transplant to prevent fatal waste build-up. Nephropathy caused by diabetes is generally more severe and tends to lead to complications more quickly than nephropathy not caused by diabetes.

KEY TERMS

Nephropathy —Kidney disease or damage.

Prevention

The best way to prevent diabetic nephropathy is to carefully control blood sugar, including eating a healthy diet and getting regular exercise. According to the American Diabetes Association, the risk of microalbuminuria is reduced by more than 30% when blood sugar is carefully controlled, and the risk that microalbuminuria would become macroalmbuninuria is reduced by 50%.

Once diabetic nephropathy has occurred, it is still possible to prevent it increasing in severity. Keeping blood pressure low, usually below 130/80 is an important part of slowing the development of the disease. Exercising regularly, eating a good diet, often one low in protein, and keeping cholesterol levels low can all help to slow the progression of the disease, or stop the progression altogether.

Caregiver concerns

Individuals with diabetic kidney disease need a lot of specialized care to ensure that the disease does not worsen to chronic kidney failure or end-stage kidney disease. Things that care givers can do to help ensure that nephropathy does not worsen include

• Ensure the individual carefully controls his or her blood sugar level.
• Have protein levels in the urine checked regularly.
• Have blood pressure checked regularly to ensure that it remains low.
• Prepare healthy meals that are low in protein.
• Help the individual get regular exercise.
• Ensure the individual takes all diabetes and blood pressure medications on time and does not accidentally skip any.

Resources

books

Cortes, Pedro, and Carl Erik Mogensen. The Diabetic Kidney. Totowa, NJ: Humana Press, 2006.

Munshi, Medha N., and Lewis A. Lipsitz. Geriatric Diabetes. New York: Informa Healthcare, 2007.

Shaw, Kenneth M., and Michael H. Cummings, eds. Diabetes: Chronic Complications, 2nd ed. Hoboken, NJ: J. Wiley, 2005.

periodicals

Lowry, Fran. “Annual Screen for Kidney Disease is Essential in Diabetic Patients.” Family Practice News 37.10 (May 15, 2007): 16.

New, Kevin. “To Predict Diabetic Nephropathy, First Look at Gums.” DOC News (May 2007): 10.

Santamarina, Marile L. “ABCs of Avoiding Microvascular Comorbidities of Diabetes.” Pharmacy Times 73.10(October 2007): 79–81.

organizations

American Diabetes Association, 1701 North Beauregard Street, Alexandria, VA, 22311, (800) 342-2383, [email protected], www.diabetes.org.

Helen Davidson