From the Guidelines
Normal microalbumin to creatinine ratio is less than 30 mg/g, while the ratio for Nephrotic Syndrome is typically greater than 300 mg/g, with albumin excretion usually greater than 2200 mg/24 h (ACR > 220 mg/g).
Microalbumin to Creatinine Ratio Categories
The following categories are used to classify albuminuria:
- A1 (Normal to mildly increased): <30 mg/g
- A2 (Moderately increased): 30-300 mg/g
- A3 (Severely increased): >300 mg/g, including nephrotic syndrome 1
Nephrotic Syndrome
Nephrotic syndrome is characterized by severely increased albuminuria, with an albumin excretion rate usually greater than 2200 mg/24 h, corresponding to an ACR > 220 mg/g 1.
Measurement of Microalbuminuria
Microalbuminuria can be measured from spot urine samples by indexing the urinary albumin concentration to the urinary creatinine concentration, with a threshold value of 30 mg/g established for the definition of microalbuminuria 1.
Clinical Significance
Microalbuminuria is a predictor of cardiovascular events and renal disease in both diabetic and non-diabetic patients, and its presence indicates a derangement in glomerular filtration barrier 1.
From the Research
Normal Microalbumin to Creatinine Ratio
- The normal microalbumin to creatinine ratio is not explicitly stated in the provided studies, but a study 2 mentions that microalbuminuria is unlikely if the microalbumin-creatinine ratio (U(MA)/U(Cr)) is below 20 microg/mg.
- Another study 3 sets the upper normal level of microalbuminuria at 15 μg/min, but does not provide a direct microalbumin to creatinine ratio.
Microalbumin to Creatinine Ratio for Nephrotic Syndrome
- A study 4 defines nephrotic syndrome as having a total protein-creatinine ratio greater than 3.5 g/g, but does not provide a specific microalbumin to creatinine ratio.
- The same study 4 mentions that equivalent thresholds for nephrotic-range albuminuria and albumin-creatinine ratio are 2.2 g/d and 2.2 g/g, respectively.
- It is essential to note that the microalbumin to creatinine ratio may not be directly equivalent to the albumin-creatinine ratio, as microalbumin and albumin are related but distinct measures of proteinuria.