Urine test: uACR (urine albumin-to-creatinine ratio)

What is the uACR test?

Why is it important to get a uACR test? 

The uACR test can be used to measure how well your kidneys are filtering out waste from your blood. Tests like the eGFR measure how much waste is being filtered out. Sometimes, the eGFR test result can be normal, but the uACR test may show kidney damage earlier. Blood creatinine levels can be affected by a person's muscle mass or the total weight of the muscle tissues in your body. People with a lower muscle mass may have an eGFR that overestimates their kidney function, while those with a higher muscle mass may have an eGFR that underestimates it. Because the uACR test measures albumin in the urine rather than creatinine in the blood, it helps provide a more accurate picture of kidney health and damage when used alongside the eGFR.

The amount of albumin in your urine can also help your doctor understand the rate at which your kidney disease is worsening and how likely it is to progress to kidney failure. In general, higher uACR levels are associated with a greater risk of worsening kidney disease, kidney failure, and heart disease. Together with your eGFR, the uACR helps your healthcare professional understand your overall kidney health and guide treatment decisions. 

How often should I get tested?

If you have diabetes, high blood pressure, or a family history of kidney disease, you may be at a higher risk of developing chronic kidney disease (CKD). For people at a high risk for CKD, it's recommended that your doctor test your kidney health with a urine and blood test at least once a year. If you've already been diagnosed with CKD, your doctor may do more frequent urine and blood tests to track any changes in kidney function and adjust your treatment plan. Talk to your doctor about developing a testing schedule that's right for you.

If you have diabetes, current guideline recommendations include getting both a uACR and an eGFR at least once a year.

How is a uACR test collected?

There are different methods to calculate your uACR, depending on how your doctor collects your urine sample. These include: 

• Spot urine sample: collected one time at a doctor's office. 
• Early morning or timed collection of urine sample: collected at home or at a doctor's office, either the first urination after waking up or collected after not urinating for four hours.
• 24-hour urine collection: collected over 24 hours if your healthcare provider needs additional information.

There are also at home uACR tests. These should not replace the tests you have done at your doctor's office or lab, but they can be a helpful way to monitor your kidney health between visits.

How do I prepare for my uACR test?  

To prepare for the uACR test, drink your usual amount of water the day before the test. This will help make sure you can urinate at the time of the test.  

Ask your healthcare provider if there is anything you should avoid before the test, such as intense exercise 24 hours before the test as it can temporarily increase albumin levels. 

What do my uACR results mean?

Your doctor will evaluate your uACR results with other tests and your overall health. If your levels are elevated, further testing or treatment may be recommended to manage and protect your kidney function.

Normal uACR

A uACR below 30 mg/g is generally considered normal healthy kidney function. It means the test found no albumin (protein) in your urine, or an amount that is normal. 

Moderate uACR 

A uACR between 30 and 300 mg/g means the test found some albumin (protein) in your urine. This presence of protein can mean your kidneys have moderate damage and are not working as well as they should. If this level remains high for 3 or more months, it may indicate you have chronic kidney disease. It's often a signal to monitor kidney health more closely, especially if you have risk factors like diabetes or high blood pressure.

Severely increased uACR  

A uACR over 300 mg/g indicates a higher level of albumin in the urine, which may be a sign of more significant kidney damage or advanced chronic kidney disease (CKD). If this level remains high for 3 or more months, it may indicate you have chronic kidney disease.

Your healthcare provider may repeat the test because temporary increases in albumin can occur with fever, urinary tract infection, intense exercise, dehydration, or having your period.

What if I have a moderately increased or severely increased uACR?  

If your uACR results are moderate or high your doctor will follow up with you. Next steps might include:

• Additional testing, like the estimated glomerular filtration rate (eGFR), to get a better idea of how well your kidneys are functioning  
• Repeated uACR testing in a few months, to see if your proteinuria levels are still high.  

What are other tests for kidney health?

uACR test results are often evaluated alongside results from the eGFR test, which is also used to evaluate kidney function and detect early signs of CKD. 

Learning about other kidney tests can empower you and your doctor to catch kidney disease early, when you can take steps to slow the damage to your kidneys. With the right tests, your doctor can identify the cause of your kidney disease, develop a treatment plan tailored to your needs, and help improve your quality of life.  

Many people receive only a blood test (eGFR) during routine checkups. However, both the uACR and eGFR are needed to provide the clearest picture of kidney health because they measure different aspects of kidney disease. If you haven't had a urine test uACR test, ask your doctor to include one.