Diabetic nephropathy Health Article

Definition

Diabetic nephropathy is a complication of diabetes. If you have this condition, your kidney loses its ability to function properly. The condition is characterized by high protein levels in the urine.

Alternative Names

Kimmelstiel-Wilson disease; Diabetic glomerulosclerosis; Diabetic kidney disease

Causes, incidence, and risk factors

Each kidney is made of hundreds of thousands of units called nephrons. Each nephron has a cluster of blood vessels called a glomerulus. The glomerulus filters blood and forms urine, which drains down into the ureter.

The earliest detectable change in the course of diabetic nephropathy is a thickening in the glomerulus. At this stage, the kidney may start allowing more albumin (protein) than normal in the urine, and this can be detected by sensitive tests for albumin. This stage is called "microalbuminuria" (micro refers to the small amounts of albumin).

As diabetic nephropathy progresses, increasing numbers of glomeruli are destroyed. Now the amounts of albumin being excreted in the urine increases, and may be detected by ordinary urinalysis techniques. At this stage, a kidney biopsy clearly shows diabetic nephropathy.

Protein may appear in the urine for 5 to 10 years before other symptoms develop. High blood pressure often accompanies diabetic nephropathy. Over time, the kidney's ability to function starts to decline. Diabetic nephropathy may eventually lead to chronic kidney failure. The disorder continues to progress toward end-stage kidney disease, often within 2 to 6 years after the appearance of high protein in the urine (proteinuria).

Diabetic nephropathy is the most common cause of chronic kidney failure and end-stage kidney disease in the United States. People with both type 1 and type 2 diabetes are at risk. The risk is higher if blood-glucose levels are poorly controlled. However, once nephropathy develops, the greatest rate of progression is seen in patients with poor control of their blood pressure.

Diabetic nephropathy generally goes along with other diabetes complications including hypertension, retinopathy, and blood vessel changes, although these may not be obvious during the early stages of nephropathy. Nephropathy may be present for many years before high protein in the urine or chronic kidney failure develop.

Symptoms

Early stage diabetic nephropathy has no symptoms. Symptoms develop late in the disease and may be a result of kidney failure or eliminating high amounts of protein in the urine.

Symptoms may include:

• Fatigue
• Foamy appearance or excessive frothing of the urine
• Frequent hiccups
• General ill feeling
• Generalized itching
• Headache
• Nausea and vomiting
• Poor appetite
• Swelling of the legs
• Swelling, usually around the eyes in the mornings; general body swelling may occur with late-stage disease
• Unintentional weight gain (from fluid build up)

Signs and tests

The first laboratory abnormality is a positive microalbuminuria test. This often means you have at least some damage to the kidney from diabetes. Damage at this stage may be reversible.

Most often, the diagnosis is suspected when a routine urinalysis shows too much protein in the urine (proteinuria) of someone with diabetes. This test may also show glucose in the urine, especially if blood sugar is poorly controlled.

High blood pressure may be present or develop rapidly. It may be difficult to control. Serum creatinine and BUN eventually may increase as kidney damage gets worse.

A kidney biopsy confirms the diagnosis. However, this test is not done if you have shown increasing protein in the urine over time and the presence of diabetic retinopathy during an eye exam. The biopsy may be done if there is any doubt in the diagnosis, and to study the extent of the disease.

This disease may also alter the results of the following tests:

• 24-hour urine protein
• Blood levels of phosphorus, calcium, bicarbonate, and potassium
• Hemoglobin
• Hematocrit
• Protein electrophoresis - urine
• Red blood cell (RBC) count