From the Guidelines
The albumin-to-creatinine ratio (uACR) should be measured annually in adults with diabetes using a morning spot urine sample. This is based on the most recent guidelines and recommendations for laboratory analysis in the diagnosis and management of diabetes mellitus, as outlined in the 2023 study published in Diabetes Care 1.
Key Points to Consider
- The uACR test is a crucial tool for detecting early kidney damage in individuals with diabetes, and its measurement is recommended annually for adults with diabetes.
- If the estimated glomerular filtration rate (eGFR) is less than 60 mL/min/1.73 m2 and/or albuminuria is greater than 30 mg/g creatinine in a spot urine sample, the uACR should be repeated every 6 months to assess changes in individuals with diabetes and hypertension.
- A moderate recommendation suggests that annual measurement of uACR is warranted if the initial result is greater than 30 mg/g, and repeat testing is reasonable after documenting stage A2 albuminuria on two of three tests performed within a period of 3 to 6 months to determine the effectiveness of chosen therapy.
Interpretation of Results
- Normal: <30 mg/g
- Microalbuminuria: 30-300 mg/g
- Macroalbuminuria: >300 mg/g The uACR is preferred over a 24-hour urine collection due to its convenience and ability to account for variations in urine concentration, providing a reliable estimate of albumin excretion and helping to detect early kidney damage before symptoms appear 1.
Clinical Implications
If an elevated uACR is found, the test should be repeated twice within 3-6 months to confirm persistent albuminuria before diagnosing chronic kidney disease, as recommended by the KDIGO and ADA guidelines 1.
From the Research
Measuring Albumin to Creatinine Ratio
The albumin to creatinine ratio (ACR) is a sensitive and early indicator of kidney damage, and it should be used routinely to accurately assess chronic kidney disease (CKD) stage and monitor kidney health 2.
When to Measure ACR
- The urine albumin creatinine ratio (UACR) detects abnormal levels of protein in the urine and should be performed annually to detect kidney disease in patients with diabetes mellitus 3.
- The ACR test is used to screen patients with chronic diseases, such as diabetes, hypertension, and cardiovascular diseases that put them at an increased risk of developing kidney disease 4.
- A single random abnormal urine albumin-to-creatinine ratio (ACR) has a good positive predictive value (PPV) for the diagnosis of CKD in patients with type 2 diabetes, so multiple random urine ACR tests might not be necessary to diagnose patients with type 2 diabetes as having persistent microalbuminuria and CKD 5.
Testing Frequency
- Annual UACR tests are recommended for patients with diabetes mellitus 3.
- However, some patients may have more than one test per year, resulting in unnecessary tests and waste 3.
- On the other hand, some patients may not have a UACR test in the previous year, potentially causing harm due to unreliable testing 3.
Testing Methods
- The ACR strip test has been evaluated as a semiquantitative point-of-care testing (POCT) assay and has shown good precision and comparable sensitivity with lower specificity than other quantitative assays 4, 6.
- The ACR strip test can be used to screen for albuminuria in cases of prediabetes and diabetes, with high sensitivity, specificity, and negative predictive value 6.