From the Guidelines
Microalbuminuria is defined as an albumin-to-creatinine ratio (ACR) of 30-300 mg/g in a urine sample. This range represents an abnormal amount of albumin excretion that exceeds normal levels but falls below the threshold for clinical proteinuria. Values below 30 mg/g are considered normal, while values above 300 mg/g indicate macroalbuminuria or overt proteinuria. Microalbuminuria serves as an important early marker of kidney damage, particularly in conditions like diabetes and hypertension, where it can precede clinically significant kidney disease by several years. The presence of microalbuminuria indicates damage to the glomerular filtration barrier, allowing small amounts of albumin to leak into the urine. Early detection through routine screening enables timely intervention with medications like ACE inhibitors or ARBs to slow progression of kidney disease and reduce cardiovascular risk, as microalbuminuria is also associated with increased cardiovascular morbidity and mortality 1.
Some key points to consider:
- Microalbuminuria is a well-established marker of increased cardiovascular risk 1.
- The definition of microalbuminuria is based on an albumin-to-creatinine ratio (ACR) of 30-300 mg/g in a urine sample 1.
- Values below 30 mg/g are considered normal, while values above 300 mg/g indicate macroalbuminuria or overt proteinuria 1.
- Microalbuminuria can be measured from spot urine samples, and the first morning spot urine sample is preferred 1.
- At least two of three tests measured within a 6-month period should show elevated levels before a patient is designated as having microalbuminuria 1.
It is essential to note that the presence of microalbuminuria indicates damage to the glomerular filtration barrier, allowing small amounts of albumin to leak into the urine. Early detection through routine screening enables timely intervention with medications like ACE inhibitors or ARBs to slow progression of kidney disease and reduce cardiovascular risk.
From the Research
Definition of Microalbuminemia
Microalbuminemia is defined as an abnormal albumin-to-creatinine ratio (ACR) in a urine sample. The normal values for ACR are:
Values for Microalbuminemia
The values for microalbuminemia are:
- 2.5 to 25 mg/mmol for males 2
- 3.5 to 35 mg/mmol for females 2
- 30-300 mg/day or 20-200 microg/min 2, 3
- ACR of 0.03 mg/mg or higher suggests microalbuminuria 3
Screening for Microalbuminemia
Screening for microalbuminemia can be done using:
- Albumin excretion rate (AER) in a timed urine sample (gold standard) 4
- Albumin:creatinine ratio in a random or first morning urine sample 5, 4
- Total urine protein-to-creatinine ratio (TPCR) as an alternative method 6
Prediction of Microalbuminemia
The total-protein-to-creatinine ratio can predict the presence of microalbuminuria in patients with diabetic nephropathy, with a significant correlation between urine total-protein-to-creatinine ratio and urine albumin to creatinine ratio (R2 = 0.824) 6