Evaluation of a Smartphone-Based Protein-to-Creatinine Ratio Assay for Detecting Kidney Disease Progression

The urine protein-to-creatinine (P/C) ratio is a rapid and accurate method for measuring proteinuria in the diagnosis of kidney diseases. A smartphone device enables rapid determination of creatinine and proteins in urine. A smartphone-based method was developed and validated for the detection of the P/C ratio in this study. Clinical urine samples were also analyzed and compared to the Beckman Coulter AU5800 results for correlation assessment. For proteinuria, the limit of blank (LOB) and limit of detection (LOD) were 4.23 and 8.8 mg/dL, respectively, with a lower limit of quantification (LOQ) of 9.2 mg/dL and a linear range from 9.2 to 122 mg/dL. The intra-batch precision coefficient of variation (CV) was 2.5%, and the inter-batch precision CV ranged from 3.0 to 3.3%. For creatinine, the LOB and LOD were 13.2 and 17.9 μmol/L, respectively, with a LOQ of 28 μmol/L and a linear range from 28 to 209.12 μmol/L. The intra-batch precision CV was between 2.7 and 2.8%, and the inter-batch precision CV was between 2.9 and 3.8%. The smartphone-based method for P/C detection is a reliable, cost-effective, and portable option for accurately measuring urinary protein and creatinine, suitable for remote diagnostics and home health checks.