Kidney Failure Risk Factor: Urine Albumin-Creatinine Ratio (uACR)

The urine albumin-creatinine ratio (uACR) shows whether you have albumin in your urine. Albumin is a type of protein that's normally found in the blood.

Your body needs protein. It's an important nutrient that helps build muscle, repair tissue, and fight infection. But it should be in your blood, not your urine. When you have albumin (protein) in your urine, it is called albuminuria or proteinuria.

One of the main jobs of your kidneys is to filter your blood. Your kidneys keep important things your body needs inside your blood, like protein. They also remove things your body doesn't need, like wastes and extra water.

If kidneys are healthy, they should let only very little protein go into your urine – or even none. But if your kidneys are damaged, protein can "leak" out of the kidneys into your urine. People with a high amount of albumin in their urine are at an increased risk of having chronic kidney disease progress to kidney failure.

The uACR is a simple urine test that's part of a routine exam. Only a small amount of your urine is needed (about two tablespoons) to do the test. Your urine will be sent to a lab. Blood or protein in the urine may be a sign of kidney disease.

A normal amount of albumin in your urine is less than 30 mg/g. Anything above 30 mg/g may mean you have kidney disease, even if your estimated glomerular filtration (eGFR) number is above 60.

A high uACR may be an early sign of kidney disease, but your healthcare team will check you again to make sure albuminuria is not caused by something else. If your healthcare team thinks you may have kidney disease, the uACR will be done again. Two high results for three months or more is a sign of kidney disease.

When you get a uACR test, a simple blood test called the estimated glomerular filtration rate (eGFR) will also be done. Your eGFR shows how well your kidneys are working.

Based on your eGFR and uACR, your healthcare team may also do one or more of these tests:

• Imaging, such as an ultrasound or CT scan to get a picture of your kidneys and urinary tract. This tells your healthcare team whether your kidneys are too large or too small, whether you have a problem like a kidney stone or tumor, and whether there are any problems in the structure of your kidneys and urinary tract.
• A kidney biopsy, which is done in some cases to check for a specific type of kidney disease. This test shows the type and amount of kidney damage there is, which helps with planning treatment. To do a biopsy, the doctor removes small pieces of kidney with a needle and looks at them under a microscope.

Your healthcare team may also ask you to see a kidney doctor, called a nephrologist, who will consult on your case and help manage your care.

• Your healthcare team will most likely prescribe a special type of blood pressure medicine that can help decrease or stop you from losing albumin in your urine. There are 2 types of this medicine. One is an ACEi (angiotensin converting enzyme inhibitor) and the other is an ARB (angiotensin receptor blocker). Even if you have normal blood pressure, you may still be told to take one of these types of medicine.
• You should follow a diet that is low in salt and sodium. This type of diet helps the blood pressure medicine work even better.

• Get your kidneys checked at least every year. Your healthcare team will do a simple blood test to find out your eGFR. They will also do a urine albumin-creatinine ratio (uACR), which shows if you have protein (albumin) in the urine. Protein in the urine may mean you have kidney damage.
• Control blood pressure if you have high blood pressure.
• Control blood sugar if you have diabetes.
• In general, if you have CKD, avoid non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and naproxen.
• If you have CKD, tell your healthcare team before having any test that uses contrast dye.
• Do not smoke.
• Exercise and follow a healthy diet that's low in sodium, saturated fat, and sugar, but high in fresh fruits, vegetables, whole grains, lean meats, fish, and poultry. Avoid highly processed foods.
• Stay at a healthy weight. Lose weight if your healthcare team says that you should.
• Discuss any vitamins, minerals, herbs, weight loss or body building supplements with your healthcare team before taking them. Many of these products can hurt your kidneys.
• Make sure that any drugs you take are the right dose for your age and your level of kidney function. You should discuss this with your healthcare team.

For more information:

• Speak with your healthcare team
• Visit the National Kidney Foundation at www.kidney.org