Kidney Health Screening:  Urine Albumin-Creatinine Ratio (uACR)

The early stages of Chronic Kidney Disease (CKD) often go unnoticed, with few recognizable symptoms to alert you to the damage your kidneys are suffering.  Unfortunately, this can make diagnosing CKD in the early stages much more problematic, and early diagnosis is key in treating Chronic Kidney Disease in order to slow, and perhaps even halt, the progression of the disease to end stage kidney failure.  The uACR is one of the basic screening tests used by your healthcare provider to look for signs that you may have CKD. If you are in a high risk category of developing chronic kidney disease, such as having diabetes, or high blood pressure, you should have these lab tests performed each year.  

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What is the uACR?

The Urine Albumin-Creatinine Ratio (uACR) is a simple lab test done by your healthcare provider. The uACR will show if you have albumin in your urine.  Albumin is a protein, and protein is important for good health. Your body needs protein to help build your muscles, repair tissue, and help fight off infections. Protein however, should be found in your blood, it should not be in your urine. Protein in the urine may indicate that you have kidney disease.  Protein (Albumin) in your urine is called Albuminuria or Proteinuria.

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Why is Albumin in the urine?

Think of your kidneys as the filter for your body. The main job of your kidneys is to filter your blood. They filter out extra water and waste products, things that your body does not need, these pass from your body in urine. The kidneys keep things, like protein, that your body does need in your blood.  Healthy kidneys are able to do a good job of filtering your blood and getting rid of waste, and healthy kidneys only let a very small amount, or none at all, of protein into your urine.  However when your kidneys are damaged, they are unable to perform their job as they should and protein can leak out of the kidneys and into your urine.  When that happens it is a signal that you may have damaged kidneys, Chronic Kidney Disease.  

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How is the uACR Test Done?

The uACR is a simple urine lab test.  Your provider will need a sample of your urine to send to the laboratory. The test can be done with just a small amount of urine.  At the lab, they will look to determine if protein is present in the urine and how much is there.

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Are There Necessary Preparations Before  uACR Test?

It is possible that there are things you might need to avoid.  Intense, vigorous exercise may increase the amount of albumin in your urine for a short time. So if you normally participate in some form of intense exercise, it is possible your healthcare provider may have you take a short break from your routine. If you have any concerns you should check with your provider to ask if there are preparations you need to make. 

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Are There Risks to the Test?

No, there is no risk to providing a sample to be tested, however, your health may be at a greater risk if the test is avoided. If you are at higher risk of developing chronic kidney disease, the earlier in the disease you are diagnosed and begin a treatment plan, the greater the chances are of slowing the progression of kidney damage and staying as healthy as possible. 

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What Does uACR Test Result Mean?

A normal amount of Albumin in your urine is less than 30mg/g.  Anything that is above 30 mg/g is a level that may indicate you have kidney disease. Your healthcare provider will most likely need more tests to confirm the results, and want to check your uACR again to make sure the Albuminuria is not being caused by something else. You may be re-tested a couple of times over a period of a few months.  

High or increasing amounts of Albumin in your urine usually mean you have kidney disease that is more serious, or in a later rather than early stage.  This also puts you at a higher risk of developing problems with your heart and blood vessels (Vascular Disease).

There are other conditions that smaller amounts of Albumin may indicate. A smaller amount of Albumin in your urine does not always mean kidney disease. There are a few other conditions that cause inflammation that may increase the Albumin in your urine.  These include Urinary Tract Infections, Periodentitis (gum disease), and Hepatitis.

A blood test called the Estimated Glomerular Filtration Rate (eGFR) will also be done.  This is also a test that will show how well your kidneys are working, filtering waste from your blood.  Based upon the results of your uACR and eGFR your healthcare provider may possibly want to have further tests performed such as Imaging, (CT or Ultrasound), or perhaps Biopsy. You may also be sent to a kidney specialist called a Nephrologist who will join your healthcare team of providers and help to manage your care and keep you healthy.

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There are some things you can do to protect your kidney function and help to prevent further kidney damage. 

• You may be prescribed a special type of blood pressure medication even if you do not have high blood pressure.  This medication may help to decrease the Albumin in your urine. 
• Have your kidneys checked at least once a year. 
• Control your blood pressure if you have high blood pressure.
• Control your blood sugar if you have Diabetes.
• Avoid NSAIDs, Non-Steroidal Anti-Inflammatory Drugs are generally to be avoided if you have CKD. These include Ibuprofen and Naproxen. 
• Do not smoke.
• Exercise and follow a healthy diet.  (You may begin to work with a dietician who can help you with a plan that will be good for your level of kidney function and keep you as healthy as possible  
• Maintain a healthy weight or lose weight if your healthcare providers believe that is best for you.  
• Discuss any vitamins, minerals, herbs, weight loss or body building supplements with your providers before taking them.  Many of these products can be harmful to your kidneys.  
• Take the correct dose of medications for your age and your level of kidney function.  Discuss anything you are taking with your healthcare provider.

Having as much information as possible about your kidney disease is important, and the uACR is a part of giving you that information. Knowing if you are in early stages of CKD or if it is likely you will reach kidney failure, gives you time to prepare, to make changes, to consider your options of treatment and to make a plan. It may help you to feel more in control of your health and your treatment plan instead of your health controlling you.  . 

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Video

This video developed by the Alila Medical Media, it provides an explanation of kidney function tests including uACR.

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‍Video Transcript

The kidneys filter blood plasma, removing  metabolic wastes and excrete them in urine.   When kidney function declines, waste  products accumulate in the blood.   Their levels can be measured in blood  tests to monitor kidney function.  

Two substances are usually measured: creatinine, a  waste product from the normal turnover of muscles;   and urea, the primary nitrogenous waste derived  from metabolism of proteins. Blood levels of these   substances RISE as kidney function declines. Blood is filtered in functional units of the   kidney called the nephrons. 

Filtration occurs  primarily in the glomerulus of the nephron.   The amount of filtrate produced per minute is  called glomerular filtration rate, GFR. GFR is   an indicator of how well the blood is filtered  by the kidneys. GFR is, however, difficult to   measure directly. In practice, it is usually  calculated as a function of serum creatinine.  

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The formula takes into account the patient’s  age, gender and race. A normal GFR is greater   than 90 mL per minute. A GFR below 60 is a sign  of reduced kidney function. A GFR smaller than 15   represents end-stage renal disease, for which  dialysis or a kidney transplant is required. 

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Urinalysis is a series of urine tests. Urinalysis  includes visual, microscopic examination of urine   samples, as well as dipstick tests, which measure  various substances in urine. The stick shows color   changes if certain substances are present or  if their levels are above normal. Urinalysis   can help detect not only renal disorders but also  urinary tract infections and other conditions such   as diabetes and liver damage. For kidney function,  albumin is tested. Albumin is a blood protein that   is not normally passed into urine. Presence of  albumin in urine is a sign of renal disease.  

Urine albumin test can be done as part of  urinalysis or as a separate dipstick test.   A positive dipstick test is usually followed  by an albumin-to-creatinine ratio test,   which provides quantitative  measurement of urine albumin   by comparing it to the amount of  creatinine in the urine sample. 

Another parameter of kidney function is creatinine  clearance, the volume of blood plasma cleared of   creatinine per minute. Creatinine clearance  test compares the creatinine in total urine   collected over 24 hours, to serum creatinine. It  can also be estimated based on serum creatinine   adjusted for age, gender and weight. Imaging tests such as ultrasound and CT   scan are used to detect obstructions, kidney  stones, tumors and abnormal kidney size.

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References

The National Kidney Foundation

National Institute of Diabetes and Digestive and Kidney Disease

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About the Author

Monica McCarthy has bachelors in Political Science and Criminal Justice from Central Washington University.  A majority of her career was spent as a political consultant.   She currently works at KidneyLuv as a staff writer.

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Patient Education Disclaimer

This material is for informational purposes only. It does not replace the advice or counsel of a doctor or health care professional. KidneyLuv makes every effort to provide information that is accurate and timely, but makes no guarantee in this regard. You should consult with, and rely only on the advice of, your physician or health care professional.

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