Microalbumin Test and Microalbumin/Creatinine Ratio

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KEY POINTS

• This urine test measures very small amounts of a protein called albumin. Your child’s liver makes albumin and the body uses it to grow and repair tissue.
• A test to check the level of creatinine in the urine is usually done at the same time. Creatinine is one of the waste chemicals in the blood that the kidney filters into the urine.
• These tests are done to check for early signs of kidney damage, especially if your child has diabetes or high blood pressure.
• You will need to collect and save all the urine your child makes in 24 hours.

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What is the microalbumin test?

This urine test measures very small amounts of a protein called albumin. Your child’s liver makes albumin, and your child’s body uses it to grow and repair tissues and to help your child’s body get rid of extra fluid.

Another test to check the level of a substance called creatinine in the urine is usually done at the same time. Then the ratio of albumin to creatinine is reported. Creatinine is one of the waste chemicals in the blood that the kidney filters into the urine.

Why is this test done?

This test is done to check for early signs of kidney damage or disease, especially in children with diabetes or with known kidney disease.

The kidneys are inside your child’s belly, on either side of the spine just above the waist. They make urine by taking waste products and extra salt and water from the blood. Normally, only very tiny substances can pass through the kidneys into the urine. Larger and more important substances that your child’s body needs, such as proteins, normally do not pass into the urine.

When the kidneys are diseased or damaged, it is easier for larger substances to pass into the urine. Albumin is one of the first larger substances to show up in the urine when the kidneys are damaged. For this reason, the microalbumin test, which can measure small amounts of protein, is a good screening test for early kidney disease.

How do I prepare my child for this test?

No special preparation is needed for this test.

Talk to your child’s healthcare provider if you have any questions about the test.

How is the test done?

A random microalbumin test measures the amount of albumin in a single sample of urine. The urine sample can also be tested for creatinine.

A total microalbumin test measures the total amount of albumin in all the urine your child’s body makes in 24 hours. For a total microalbumin test, you need to collect and save all the urine your child makes in 24 hours.

To collect this urine sample:

• Have your child urinate into the toilet right after your child gets up on the day your child starts the test. Do not save this urine.
• After that, collect all the urine your child passes for the next 24 hours. Keep the urine cool by storing it capped in the refrigerator or in another cool place.
• On the second day of the test, get your child’s last sample of urine when your child gets up, cap the container, and take it to the lab.

Ask your child’s healthcare provider when and how you will get the result of your child’s test.

What does the test result mean?

When your child’s kidneys are healthy, very little albumin is present in the urine and the microalbumin/creatinine ratio is low. The level of albumin in your child’s urine may be higher than normal because of kidney disease. Causes of kidney disease may include:

• Diseases a child is born with such as polycystic kidneys
• Urine blockage or reflux
• Infections such as hemolytic uremic syndrome, caused by E. coli bacteria
• Autoimmune disorders such as lupus
• Injuries such as serious burns or bleeding that decrease blood flow to the kidneys

Sometimes your child may have more albumin in the urine after strenuous exercise or when your child has not been drinking enough fluids.

Things that can lead to incorrect results are fever, infection, blood in the urine, and high blood glucose (sugar). The test may need to be repeated to check the results.

What if my child’s test result is not normal?

Test results are only one part of a larger picture that takes into account your child’s medical history, physical exam, and current health. Sometimes a test needs to be repeated to check the first result. Talk to your child’s healthcare provider about the results and ask questions, such as:

• If your child needs more tests
• What kind of treatment your child might need
• What lifestyle, diet, or other changes your child might need to make