Albuminuria

Albumin is a protein. Albuminuria (Al-byoo-mih-noo-ree-uh) is having too much protein in the urine. This is sometimes referred to as "microalbuminuria" which indicates a slightly high level of protein in the urine. Overt proteinuria or "macroalbuminuria" indicates more than 300mg of albumin in the urine per day.

Persistent albuminuria means that the kidney has some damage and is starting to spill some albumin into the urine. Two positive tests for albumin in the urine over several weeks indicate persistent albuminuria, a first sign of diabetic kidney disease. Other causes of albuminuria are high blood pressure, congestive heart failure, the metabolic syndrome, or kidney damage from nephrotic syndrome. Even without these diseases, having a higher than normal levels of albumin in the urine is a risk factor for cardiovascular disease, according to the Framingham Health Study.

Although urinary albumin screening of asymptomatic individuals at risk can detect early kidney disease, measurement of albuminuria can identify some but not all patients with kidney disease. However, in patients with diabetes and/or established chronic kidney disease, albuminuria is associated with more rapid progression of their chronic kidney disease and a greater chance that kidney failure will develop.

How many people have this problem?

About 8 percent of adults have microalbuminuria (i.e. excretion of 30 to 300 mg of albumin per 24 hours) and 1 percent have macroalbuminuria (i.e. excretion of more than 300 mg of albumin per 24 hours). Albuminuria was detected in one of every three persons with diabetes, one of every seven persons with high blood pressure but no diabetes, and one of every six persons older than 60 years. [These statistics are from the NHANES study.]

How is albuminuria measured?

It is recommended that doctors screen for kidney disease using a random urine sample to detect protein. Protein is easily and quickly found with urine dipstick testing. If this screening test is negative, a more precise urine test can be preformed which measures a ratio called the albumin-to-creatinine in a random urine sample. The albumin—creatinine ratio in an early-morning random urine sample is considered accurate, but sometimes a 24-hour urine collection may be done to measure albuminuria. Albuminuria can also be measured by using an albumin-specific dipstick on a random urine sample. Any doctor can test for albuminuria.

Who should have this test and how often?

Everyone with Type I and Type 2 diabetes who is between 12 and 70 years of age should have a urine test for albuminuria at least once a year. Current guidelines recommend screening for albuminuria in patients with risk factors for chronic kidney disease, including diabetes, high blood pressure, systemic illnesses, age greater than 60 years, and family history of kidney failure. lf positive, the result should be confirmed by a second urine test.

What would be considered a positive result?

ln a single urine specimen, a level of more than 30 mg of albumin per gram of creatinine is considered positive. For a 24-hour urine collection, 30 to 300 mg of albumin means albuminuria.

Can anything besides kidney disease cause this test to be positive?

Yes; some other conditions such as high blood pressure can also cause albuminuria. If the test is done during periods of illness, heavy exercise, urinary tract infections or poor blood glucose sugar control, it may show a positive result. People who smoke can have a positive test. In some people without kidney disease, upright standing can result in a positive test for albuminuria.

ls the test for urine albumin expensive? ls it covered by health insurance?

The test is relatively inexpensive and most health insurance plans will cover it.

Does a positive test suggest other problems besides kidney disease?

Albuminuria suggests a higher risk for heart disease as well as kidney disease in people with and without diabetes or other chronic disease.

Is diabetic kidney disease serious?

Kidney disease is one of the most serious complications of diabetes. After years of diabetes, the filtering units of the kidney—called glomeruli—get scarred and cannot filter the blood efficiently. Eventually, the kidneys may fail completely so that a person with the disease needs hemodialysis, peritoneal dialysis or a kidney transplant to survive.

Are there tests that can tell if my kidneys have been hurt by diabetes?

Yes: a urine test for albumin and a blood test for creatinine. The results of the creatinine blood test should be used to estimate glomerular filtration rate (GFR), which is a measure of your level of kidney function.

What can be done to prevent diabetic kidney disease?

Tight control of glucose lowers the risk of all diabetic complications, including kidney disease. Other measures are: keeping high blood pressure under good control quitting cigarette smoking and following a diabetic diet, as prescribed by your doctor or health care professional. In addition to these measures, once diabetic kidney disease and albuminuria have developed, medications called angiotensin converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB) should be prescribed to slow down the progression of diabetic kidney disease.

Date Reviewed: September 2009

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©2014 National Kidney Foundation. All rights reserved. This material does not constitute medical advice. It is intended for informational purposes only. Please consult a physician for specific treatment recommendations.