What is the Difference Between ACR and PCR

ACR and PCR are two noninvasive urine tests performed when someone is suspected to have proteinuria. In healthy persons, urine contains very little amount of protein, which is less than 150 mg/day. Proteinuria is a state where there is an excess protein in urine. It can be caused by relatively harmless conditions and more serious conditions like kidney disease or immune disorders. Proteinuria can be diagnosed through noninvasive, harmless urine tests such as ACR and PCR.

The key difference between ACR and PCR is the occasion on which they are used. ACR is a test performed when albumin proteinuria is suspected, while PCR is a test performed when non-albumin proteinuria is suspected.

1. Overview and Key Difference
2. What is ACR
3. What is PCR
4. Similarities – ACR and PCR
5. ACR vs PCR in Tabular Form
6. Summary – ACR vs PCR
7. FAQ – ACR and PCR

What is ACR?

ACR (Albumin: Creatinine Ratio) is the preferred test for the detection of small amounts of albumin in the urine. However, it can be performed when people also have macroalbuminuria. Microalbuminuria occurs when a small amount of albumin is present in the urine. It is a sign of kidney disease and cardiovascular disease. A healthcare provider may also order a microalbuminuria test if people have diabetes or high blood pressure.

An ACR test result is the ratio of measured albumin (a protein) and creatinine (a metabolism by-product) in the urine that has been excreted from the body. The severity of ACR levels is indicated as microalbuminuria and macroalbuminuria. ACR levels for males 2.5 to 25 (mg/mmol) means microalbuminuria, while greater than 25 indicates macroalbuminuria. ACR levels for females 3.5 to 35 (mg/mmol) means microalbuminuria, while greater than 35 indicates macroalbuminuria. The benefits of the ACR test include its cost-effectiveness, accuracy, and early diagnosis of CKD state. There is extremely little risk of having an ACR test, and it costs around $47.

What is PCR?

PCR (Protein Creatinine Ratio) is a test that gives information about how the kidneys are working. It measures the levels of protein and creatinine in urine. This test is ordered if people have signs of preeclampsia and at a routine physical examination to screen for proteinuria. Normal urine elimination is less than 150 mg total protein per day and less than 30 mg albumin daily. The urine total protein to creatinine ratio or PCR (mg/mg) is usually less than 0.2 for adults.

This is a noninvasive test, so there are no prominent risks while taking the urine protein creatinine ratio test. This test has multiple benefits, such as being non-invasiveness or painless, multiple uses, monitor treatments, and a dual value. Furthermore, this test cost around $49.

Figure 02: PCR

Similarities Between ACR and PCR

ACR and PCR are two tests performed when proteinuria is suspected.
Both tests are urine tests.
In both tests, a 24-hour urine sample is collected.
Both tests have a dual value.
They are noninvasive tests.
Both tests are cheap.

Difference Between ACR and PCR

Definition

ACR test is the preferred test for detection of small amounts of albumin in the urine.
PCR test is the preferred test where non-albumin proteinuria is suspected.

Test Result

ACR for men: 2.5 to 25 means microalbuminuria, while > 25 indicates macroalbuminuria; ACR for females: 3.5 to 35 means microalbuminuria, while > 35 indicates macroalbuminuria.
PCR is usually less than 0.2 for normal adults.

Used to Diagnose

ACR tests are used to diagnose CKD and cardiovascular disease.
PCR tests are used to diagnose kidney function and kidney disease.

Benefits

ACR tests are cost-effective, accurate, and help in the early diagnosis of CKD.
PCR tests are noninvasive, using small amounts of urine to check for various diseases and disorders affecting kidney function, monitor treatment efficacy, and provide dual diagnostic value.

Cost

An ACR test is around $47.
A PCR test is around $49.

The following table summarizes the difference between ACR and PCR.

Summary – ACR vs PCR

Proteinuria is high levels of protein in the urine. ACR and PCR are two tests performed when proteinuria is suspected. ACR measures albumin to creatinine ratio that only accounts for albumin concentration divided by urine creatinine. PCR measures the protein creatinine ratio, which accounts for the total urine protein concentration (albumin, light chains, and other globulins) divided by urine creatinine. Furthermore, an ACR test is ordered when albumin proteinuria is suspected, while a PCR test is ordered when non-albumin proteinuria is suspected. This is the summary of the difference between ACR and PCR.

FAQ: ACR and PCR

1. How do you calculate ACR?

To determine the ACR test ratio, the heath care provider divides urine albumin concentration by creatinine concentration, then converts it to mg/g.

2. What is the limit for ACR?

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

3. What is normal PCR?

UPCR < 0.2 g/g Cr is considered a criterion for normal for adults. Instead, urine PCR ≥ 2.0 g/g Cr can be considered a criterion for nephrotic range proteinuria or nephrotic syndrome in children.

4. What is the significance of the PCR test?

PCR test gives important information about how the kidneys are working. This urine test is quick, painless and noninvasive. The results of PCR test can help diagnose and monitor conditions that can damage the kidneys.

5. How does it calculate the PCR?

In this test, a urine specimen is assayed for urine protein concentration and urine creatinine concentration. Then, the PCR test ratio is calculated by dividing the urine protein concentration by the creatinine concentration.

Reference:

1. “ACR Test.” NHS Choices, NHS.
2. “Urine Protein Creatinine Ratio (UPCR): Test & Results.” Cleveland Clinic.

Image Courtesy:

1. “Urine sample for Culture and Sensitivity” By Ajay Kumar Chaurasiya – Own work (CC BY-SA 4.0) via Commons Wikimedia

CONTENTS

What is ACR?

What is PCR?

Similarities Between ACR and PCR