From the Guidelines
Albuminuria testing should be performed annually in adults with diabetes using the morning spot urine albumin-to-creatinine ratio (uACR) as the gold standard, as recommended by the most recent guidelines 1. The current approach to albuminuria testing emphasizes the importance of early detection and monitoring of kidney disease, particularly in high-risk populations such as those with diabetes.
Key Recommendations
- Annual testing for albuminuria should begin in pubertal or post-pubertal individuals 5 years after diagnosis of type 1 diabetes and at the time of diagnosis of type 2 diabetes, regardless of treatment 1.
- The uACR should be measured annually in adults with diabetes using morning spot urine albumin-to-creatinine ratio (uACR) 1.
- If estimated glomerular filtration rate is <60 mL/min/1.73 m2 and/or albuminuria is >30 mg/g creatinine in a spot urine sample, the uACR should be repeated every 6 months to assess change among people with diabetes and hypertension 1.
Testing Methods
- Semiquantitative uACR dipsticks can be used to detect early kidney disease and assess cardiovascular risk when quantitative tests are not available, with a recommended sensitivity of >85% for detecting moderately increased albuminuria 1.
- First morning void urine sample should be used for measurement of albumin-to-creatinine ratio, and if this is not possible, all urine collections should be at the same time of day, with the individual well hydrated and not having ingested food within the preceding 2 hours or exercised 1.
Clinical Implications
- The classification system for albuminuria has been standardized, with categories of normal (<30 mg/g creatinine), moderately increased (30-300 mg/g), and severely increased (>300 mg/g), allowing for better risk stratification and treatment planning for patients with early signs of kidney disease.
- Positive urine albumin screening results by semiquantitative tests should be confirmed by quantitative analysis in an accredited laboratory 1.
From the Research
Development in Albuminuria Testing
- Albuminuria is an important risk marker for adverse cardiovascular and renal outcomes, and mortality 2.
- The relationship between albuminuria and risk is continuous and linear, and evidence supports increased risk even at levels traditionally considered within normal limits 2.
- Routine annual screening can detect changes in urine albumin excretion and improve the timely identification of albuminuria, especially in high-risk patients with diabetes, hypertension, and chronic kidney disease 2.
Screening Methods
- Preferred simple screening methods for albuminuria include microalbumin-specific dipsticks and urinary albumin:creatinine ratio determination (from a spot urine sample) 2.
- Urine albumin concentration and albumin to creatinine ratio are acceptable tests for population screening for albuminuria in Indo-Asians, although sensitivities may be suboptimal, particularly in women 3.
- Estimated albumin excretion rate (eAER) using spot albumin-creatinine ratio and estimated creatinine excretion rate may improve albuminuria assessment, especially in patients with extremes of muscle mass 4.
Comparison of Screening Methods
- The urine dipstick test has poor sensitivity and high false-discovery rates for detecting albuminuria compared to albumin:creatinine ratio (ACR) assessments 5.
- ACR assessments classify a large number of individuals into different chronic kidney disease (CKD) risk categories compared with dipstick-based categories, and appear beneficial for a more accurate prediction of worse quality of life 5.
Treatment and Management
- Cornerstones of albuminuria treatment include risk factor management, ongoing monitoring, and the use of renin-angiotensin-aldosterone system (RAAS)-blocking agents, such as angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) 2.
- ARBs may be preferred for diabetic patients with albuminuria due to their renoprotective effects, which reduce the risk of end-stage renal disease (ESRD) and doubling of the serum creatinine level 6.