From the Guidelines
Elevated Albumin to Creatinine Ratio (ACR) in urine is primarily caused by kidney damage, with factors such as diabetes, hypertension, and glomerulonephritis being common causes, as well as temporary elevations due to exercise, infection, fever, and marked hypertension. When considering the etiology of an elevated ACR, it is essential to note that a single measurement may not be sufficient due to high biological variability of >20% between measurements in urinary albumin excretion, as noted in the 2022 standards of medical care in diabetes 1. According to the same study, two of three specimens of UACR collected within a 3- to 6-month period should be abnormal before considering a patient to have high or very high albuminuria 1. Some factors that may elevate ACR independently of kidney damage include:
- Exercise within 24 h
- Infection
- Fever
- Congestive heart failure
- Marked hyperglycemia
- Menstruation
- Marked hypertension, as mentioned in the study 1. It is crucial to consider these factors when interpreting ACR results to ensure accurate diagnosis and management of kidney disease. In clinical practice, an eGFR persistently <60 mL/min/1.73 m2 in concert with a urine albumin value of >30 mg/g creatinine is considered abnormal, though optimal, and referral to a nephrologist may be necessary for uncertainty about the etiology of kidney disease or difficult management issues 1.
From the Research
Causes of Elevated Albumin to Creatinine Ratio (ACR)
- Elevated ACR levels can be associated with various factors, including age, markers of adiposity and insulin secretion and resistance, blood pressure, and use of antihypertensive agents with antiproteinuric effects 2
- The presence of chronic kidney disease (CKD) can also lead to elevated ACR levels, as albuminuria is a key marker of CKD 3, 4
- Diabetes is another factor that can contribute to elevated ACR levels, as individuals with type 2 diabetes are at increased risk of developing CKD and albuminuria 2, 5
- The use of certain medications, such as angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers, can also affect ACR levels 4, 5
Factors Influencing ACR Levels
- Quartiles of ACR were positively associated with age, markers of adiposity and insulin secretion and resistance, blood pressure, and use of antihypertensive agents with antiproteinuric effects 2
- An elevated hazard rate for developing diabetes with doubling of ACR disappeared after adjustment for covariates, suggesting that other factors may play a role in the development of diabetes 2
- The prescription of renin-angiotensin system blockade was associated with higher ACR levels, with a steep increase in prescriptions until ACR 300 mg/g, after which the association plateaued 4
Diagnostic Accuracy of ACR Tests
- The diagnostic accuracy of a urine albumin-creatinine ratio point-of-care test for detection of albuminuria in primary care was found to be moderate, with a sensitivity of 83.2% and specificity of 80.0% 6
- The positive predictive value of a single random abnormal urine ACR was found to be high, at 96.80%, suggesting that a single test may be sufficient for diagnosis in patients with type 2 diabetes 5