Why is a protein-to-creatinine ratio (Protein/Creatinine) ordered?

From the Guidelines

The protein creatinine ratio (PCR) is ordered to assess and monitor kidney function by measuring the amount of protein being excreted in the urine, which is a crucial marker for detecting kidney disease, particularly in conditions like diabetic nephropathy, preeclampsia, and chronic kidney disease 1.

Key Points:

• The PCR test is preferred over a 24-hour urine collection due to its convenience, requiring only a single urine sample.
• A normal PCR is typically less than 0.2 mg protein/mg creatinine, with values above this suggesting kidney damage.
• The test works by comparing the concentration of protein to creatinine in the urine, as creatinine is excreted at a relatively constant rate.
• Elevated levels of protein in the urine indicate damage to the kidney's glomerular filtration barrier.
• The PCR is especially useful for monitoring disease progression and response to treatment in patients with kidney disease.

Clinical Application:

• The PCR test is useful for detecting proteinuria, which is an abnormal amount of protein in the urine that may indicate kidney disease.
• Clinicians use the PCR test to assess disease progression and response to treatment by providing a quantitative measure of proteinuria.
• The test is also used to monitor conditions like diabetic nephropathy, preeclampsia in pregnant women, and chronic kidney disease.

Evidence-Based Recommendation:

• The protein creatinine ratio (PCR) should be used to assess and monitor kidney function in patients with kidney disease, as it provides a convenient and accurate measure of proteinuria 1.

From the Research

Reasons for Ordering Protein Creatinine Ratio

• The protein creatinine ratio (PCR) is used to assess proteinuria, which is an important indicator of chronic kidney disease (CKD) 2.
• Proteinuria is defined as the presence of excess proteins in the urine, and it can be a sign of kidney damage or disease 2.
• The PCR test measures the amount of protein in the urine relative to the amount of creatinine, which is a waste product that is normally excreted by the kidneys 3.
• A high PCR result can indicate kidney damage or disease, and it can be used to monitor the progression of CKD 4.
• The PCR test is often used in conjunction with other tests, such as the albumin creatinine ratio (ACR) test, to assess kidney function and diagnose CKD 2.

Comparison with Albumin Creatinine Ratio

• The ACR test measures the amount of albumin, a specific type of protein, in the urine relative to the amount of creatinine 2.
• The PCR test measures the total amount of protein in the urine, including albumin and other types of proteins 4.
• Studies have shown that the PCR test is more sensitive than the ACR test for detecting proteinuria, especially in patients with non-diabetic CKD 4.
• However, the ACR test may be more specific for detecting albuminuria, which is a specific type of proteinuria that is associated with an increased risk of CKD progression 2.

Clinical Significance

• Proteinuria is a significant predictor of CKD progression and cardiovascular disease 2.
• The PCR test can be used to monitor the effectiveness of treatments for CKD, such as angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) 5, 6.
• Early detection and treatment of proteinuria can help to slow the progression of CKD and reduce the risk of cardiovascular disease 2.