From the Guidelines
The microalbumin/creatinine ratio is a crucial test for detecting early kidney damage, with values between 30-300 mg/g indicating microalbuminuria and values above 300 mg/g indicating macroalbuminuria, and should be used to guide treatment decisions, including the use of ACE inhibitors or ARBs, such as lisinopril 10-40 mg daily or losartan 25-100 mg daily, to slow disease progression 1.
Importance of Microalbumin/Creatinine Ratio
The microalbumin/creatinine ratio is an important test that measures the amount of albumin (a protein) in urine compared to creatinine, helping to detect early kidney damage. A normal ratio is less than 30 mg/g.
Interpretation of Results
Values between 30-300 mg/g indicate microalbuminuria, suggesting early kidney damage, while values above 300 mg/g indicate macroalbuminuria and more significant kidney damage.
Monitoring and Treatment
This test is particularly important for monitoring patients with diabetes, hypertension, or other conditions that put them at risk for kidney disease. For diabetic patients, annual screening is recommended starting at diagnosis for type 2 diabetes and after 5 years of disease for type 1 diabetes.
- If elevated levels are detected, treatment typically includes:
- Optimizing blood pressure control (target <130/80 mmHg)
- Using ACE inhibitors or ARBs
- Improving glycemic control in diabetics (target HbA1c <7%)
- Lifestyle modifications including sodium restriction, weight loss, and smoking cessation
Rationale for Treatment
The test works because healthy kidneys prevent albumin from passing into urine, so its presence indicates that the kidney's filtering system (glomeruli) is damaged, allowing protein to leak into the urine before other symptoms of kidney disease appear, as supported by the European guidelines on cardiovascular disease prevention in clinical practice 1.
Frequency of Monitoring
The frequency of monitoring should be guided by the severity of CKD and the risk for progression, with more frequent monitoring for those at higher risk, as outlined in the Kidney Disease: Improving Global Outcomes 2012 clinical practice guideline 1.
From the Research
Microalbumin/Creatine Ratio
- The microalbumin/creatinine ratio is a widely accepted biomarker of early diabetic kidney disease (DKD) 2.
- A ratio of >30 and <300 mg/g is considered indicative of microalbuminuria, which is a marker of endothelial injury 2.
- However, some studies suggest that microalbuminuria may not be the earliest event in DKD, and that tubular proteinuria may precede it 2.
- The presence of microalbuminuria is associated with an increased risk of end-stage renal disease and cardiovascular disease 3, 4.
Measurement and Interpretation
- The microalbumin/creatinine ratio can be measured using a spot urine sample, and a ratio of >30 mg/g is considered positive for microalbuminuria 5.
- The ratio is calculated by dividing the amount of albumin in the urine by the amount of creatinine 5.
- A study found that spot urine albumin to creatinine ratio and serum cystatin C are effective for detection of diabetic nephropathy in childhood diabetic patients 6.
Risk Factors
- Hypertension, obesity, sedentary lifestyles, and duration of diabetes >5 years are significant risk factors for the development of microalbuminuria in diabetes 5.
- Smoking and physical activity are also associated with microalbuminuria, with a significant association seen between microalbuminuria and BMI, duration of DM, hypertension, smoking, and physical activity 5.