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Microalbuminuria

Published by Bupa's health information team, February 2008.

This factsheet is for people whose urine test has shown a raised level of a type of protein called albumin. This condition is called microalbuminuria.

Microalbuminuria is where very small (trace) amounts of the protein albumin pass through your kidneys and into your urine. This can be a sign of underlying conditions such as kidney problems or cardiovascular disease.

About microalbuminuria
Causes
Diagnosis
Treatment
Further information
Questions and answers
Related topics
Sources

About microalbuminuria

Your blood contains cells and proteins that your body needs as well as waste products that your body needs to get rid of. The waste products within your blood are filtered by your kidneys and are removed in your urine. Usually the cells and proteins stay in your blood, but sometimes a small amount of protein is lost into your urine with the other waste products.

Microalbuminuria is where the level of the protein albumin in your urine is continuously slightly raised. It's defined by 30 to 300mg of albumin being lost in the urine per day. This is different to proteinuria, which is when the levels of protein in the urine are higher than 300mg a day.

It's estimated that 15 percent of people with type 1 diabetes and 25 percent of people with type 2 diabetes will have microalbuminuria.

Why is it important?

An increased level of albumin in your urine shows that the blood vessels that are involved in filtering waste products in your kidneys are damaged.

Microalbuminuria may be the first sign of kidney disease or that the kidney is damaged. People with type 1 and type 2 diabetes can have kidney damage as a complication of their diabetes. It may also be a sign of more widespread damage to blood vessels, including those of the heart. So it can be a sign of an increased risk of heart disease, particularly if you have type 2 diabetes.

The good news is that if you have diabetes and your microalbuminuria is detected early, there are treatments that can reduce the damage and slow the decline in your kidney function.

Causes

The development of microalbuminuria has been linked to long-term control of blood glucose (sugar) levels. As well as diabetes, other risk factors for developing microalbuminuria include:

high blood pressure
family history of diabetic kidney disease
smoking
being overweight

Diagnosis

Ordinary urine tests designed to test for protein and albumin don't pick up the low levels of albumin that are present in microalbuminuria. More specialised tests are needed, which include the following.

Albumin:creatinine ratio (ACR) test

This is the preferred test for microalbuminuria. It involves taking a sample of your urine and sending it to a laboratory for tests. You may be asked to collect your urine sample first thing in the morning. A person will be diagnosed as having microalbuminuria if their ACR is:

2.5mg/mmol or higher (for men)
3.5mg/mmol or higher (for women)

24-hour urine sample

The final test may take the form of collecting your urine over a 24-hour period and sending it to a laboratory for analysis. This gives an accurate measurement of how much albumin has been lost in your urine during a day.

The 24-hour urine sample is considered to be the best way for accurately diagnosing microalbuminuria. However, it isn't used as a screening test because collecting your urine over a full 24-hour period can be inconvenient - as a result the urine samples collected for this test are often incomplete and difficult to interpret.

Using this test, microalbuminuria is defined as having 30 to 300mg of albumin in the urine a day.

The test results can be affected by:

recent exercise (within 24 hours of the test)
urinary tract infection
heart failure
uncontrolled blood sugar levels
blood in the urine

You should tell your nurse or doctor if you have any of these problems, or have exercised within a day of being due to start collecting your urine, so that the test can be re-arranged for another day.

Treatment

There are a number of lifestyle changes that can help slow the rate of kidney damage.

If you have diabetes, you need to monitor and control your blood glucose levels.
Keep your blood pressure as low as possible. Medicines such as ACE inhibitors and angiotensin receptor blockers have been shown to slow down kidney damage.
Don't smoke.
Eat a healthy, balanced diet.
Maintain a healthy weight - lose weight if you are overweight or obese.

Further information

Diabetes UK
020 7424 1000
www.diabetes.org.uk