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Urine Test: Microalbumin-to-Creatinine Ratio

What It Is

A microalbumin-to-creatinine ratio urine test involves measuring the amount of a protein called albumin in the urine. The amount of urine albumin is compared with the quantity of a waste product in the urine called cretonne.

The body normally filters out creatinine in the urine at a steady rate, so comparing the ratio of urine albumin with creatinine in the same urine specimen helps determine if the body is excreting albumin at an increased rate. If this is occurring it may be the result of kidney disease.

In most healthy people, the kidneys prevent albumin and other proteins from entering the urine. However, if kidneys are damaged and start to allow proteins to pass from the blood into the urine, the first type of protein to appear in the urine is albumin. This is because albumin molecules are smaller than most other protein molecules.

The consistent presence of small amounts of albumin in the urine is called microalbuminuria and is associated with early-stage kidney disease. Once there are larger amounts of albumin in the urine it is called macroalbuminuria and it could indicate more severe kidney disease.

Why It's Done

The microalbumin-to-creatinine ratio test is most commonly used to screen for kidney problems in teens with diabetes. It also might be done on a more regular basis, like once a year, in teens with diabetes to help in early identification of kidney disease.

It also can be used to monitor kidney function in kids and teens already diagnosed with kidney disease or taking medications that can affect the kidneys. The test can also help detect kidney complications from hypertension and autoimmune diseases.

Preparation

Your child might need to temporarily stop taking specific drugs that could interfere with test results. Be sure to review all your child's medications with your doctor.

The Procedure

Your child will be asked to urinate (pee) into a clean sample cup in the doctor's office or at home. Collecting the specimen should only take a few minutes. If your child isn't potty trained and can't urinate into a cup, a catheter (a narrow, soft tube) may need to be inserted into the bladder to obtain the urine specimen.

A urine collection bag with adhesive tape on one end might instead be used to collect a sample from an infant. If you're doing the collection at home, you'll clean your baby's genital area and then attach the bag around the urinary opening. Once the bag is in place, you'll secure it with the attached tape. You can put a diaper on your baby once you've attached the bag. Remove the collection bag after your baby has urinated into it, usually within an hour. Deliver this specimen to your lab.

Sometimes, a doctor will want to test urine collected over a period of time ranging from 4 to 24 hours. After each urination, you or your child will pour the specimen from the sample cup into a larger container. Be careful not to touch the inside of the container. During the testing period, all the urine should be collected, even if it is just a small amount.

For specimens collected at home, follow any storage and transportation instructions the lab gives you. At the lab, the technician will determine the quantity of albumin in the urine and compare it with the amount of creatinine in the urine.

What to Expect

Because the test involves normal urination, there shouldn't be any discomfort as long as your child can provide a urine specimen. It's important to keep the area around the urinary opening clean before the test.

Getting the Results

The results of the microalbumin-to-creatinine test will be available in 1-3 days. It's important to know that children sometimes pass albumin in their urine even though they have no kidney damage.

If the test shows abnormal results, further tests will be ordered to determine if there's an illness and, if so, help diagnose it. Talk to your doctor about the meaning of the specific test results.

Risks

No risks are associated with the urine microalbumin-to-creatinine ratio test. Infants may occasionally experience skin irritation from the adhesive tape on the collection bag. If a catheterized specimen is required it may cause temporary discomfort.

You can discuss any questions you have about this procedure with your doctor.

Helping Your Child

The urine microalbumin-to-creatinine ratio test is painless. Explaining in simple terms how the test will be conducted and why it's being done, can help ease any fear. Make sure your child understands that there should be no foreign matter, such as toilet paper or hair, in the sample.

If You Have Questions

If you have questions about the microalbumin-to-creatinine ratio test, speak with your doctor.

Reviewed by: Yamini Durani, MD
Date reviewed: March 2012