Variability of UACR in Patients With T2D

Albuminuria is known as a leading diagnostic and prognostic marker of diabetic chronic kidney disease. However, its day-to-day variability has not been sufficiently considered, so Natasha Rasaratnam, MD, and other researchers conducted a cross-sectional analysis to quantify the within-individual variability of albuminuria in patients with type 2 diabetes (T2D) to help guide clinical albuminuria monitoring. 

The study included individuals who took part in the Progression of Diabetic Complications cohort study and had T2D. There were 826 study participants, 64.9% of whom were male; median age was 67.1 years (interquartile range, 60.3-72.4). To examine the variability of urinary albumin-creatinine ratio (UACR), four spot urine samples were collected within 4 weeks for measurement.  

There was a high variability of UACR within individuals (coefficient of variation, 48.8%; 95% limits of random variation found a repeated UACR to be as high/low as 3.78/0.26 times the first). When a single-collection UACR increased from 2 to 5 mg/mmol, the probability that UACR increased by at least 30% was only 50%; this rose to 97% when two samples were taken at each time point. The ranges of diagnostic uncertainty were 2.0-4.0 mg/mmol after an initial UACR test, which narrowed to 2.4-3.2 and 2.7-2.9 mg/mmol for the mean of two and three collections, respectively.  

Female sex and moderately increased albuminuria corresponded with higher within-individual UACR variability. Reduced estimated glomerular filtration rate and treatment with sodium-glucose cotransporter 2 inhibitor, angiotensin-converting enzyme inhibitor, or angiotensin receptor blocker correlated with lower within-individual UACR variability. 

Taking multiple urine samples to measure UACR may help with monitoring changes over time in clinical and research settings. However, this approach may not be necessary for diagnosing albuminuria. 

 Source: American Journal of Kidney Diseases