From the Guidelines
The Creatinine (Creat)/Albumin ratio, also known as the Albumin-to-Creatinine Ratio (ACR), is a crucial test for assessing kidney function and detecting early signs of kidney damage, particularly in patients with diabetes, as it is a continuous marker for cardiovascular event risk at all levels of kidney function 1.
Indications for Calculating the Creat/Albumin Ratio
The test is typically indicated in patients with:
- Diabetes, as annual albuminuria testing is recommended at the time of diagnosis for type 2 diabetes, and 5 years after diagnosis for type 1 diabetes 1
- Hypertension or other conditions that increase the risk of kidney disease
- Family history of kidney disease
- Symptoms such as swelling, fatigue, or blood in the urine
- Patients taking medications that may affect kidney function, such as nonsteroidal anti-inflammatory drugs (NSAIDs) or certain antibiotics
Interpretation of Results
The ACR test results are categorized into three stages:
- A1—Normal to Mildly Increased Albuminuria: uACR <30 mg/g (<3 mg/mmol) 1
- A2—Moderately Increased Albuminuria: uACR 30 to 299 mg/g (3 to 29 mg/mmol) 1
- A3—Severely Increased Albuminuria: uACR ≥300 mg/g (≥30 mg/mmol) 1 These categories help identify the level of kidney damage and guide treatment decisions.
Clinical Significance
The ACR test is essential for early detection and management of kidney disease, as it allows for timely interventions to slow disease progression and reduce cardiovascular risk 1. It is crucial to consult a healthcare provider to determine the best course of action and to interpret the results of the ACR test.
From the Research
Significance of Creatinine (Creat)/Albumin Ratio
- The Creatinine (Creat)/Albumin ratio, also known as the Albumin-to-Creatinine Ratio (ACR), is a significant marker of kidney damage and is used for prognosis in persons with chronic kidney disease (CKD) 2.
- ACR is used to measure urine protein and is an important prognostic marker in kidney disease, predicting graft failure and patient death after kidney transplant 3.
- The ratio is also used to identify and monitor kidney damage, and significant interassay differences in urinary albumin quantification have been documented, which may affect ACR 4.
Indications for Calculating ACR
- ACR is used to predict the risk of kidney failure and is endorsed by recent guidelines 5.
- The ratio is used to estimate kidney function after kidney transplant and has been shown to have a strong linear relationship with estimated glomerular filtration rate (eGFR) 3.
- ACR is also used to screen for albuminuria in cases of prediabetes and diabetes, with high sensitivity, specificity, and negative predictive value 6.
- The ratio can be estimated from the protein-to-creatinine ratio (PCR) using equations developed from same-day measurements, allowing for modification by specified covariates 5.
Clinical Applications
- ACR is used in clinical practice to manage immediate complications of CKD, with routine measurement of PCR providing similar information as ACR 2.
- The ratio is used to monitor kidney damage and predict graft function after kidney transplant, with a simple and effective measure to predict graft function 3.
- ACR is also used to screen for albuminuria in high-risk populations, such as those with prediabetes and diabetes, and can be used to predict the occurrence of nephropathy and cardiovascular disorders 6.