B-038 Configuration and validation of urine citrate open channel assay on the Roche Cobas c503

Background Measuring urine citrate plays a key role in evaluating kidney stone risk and overall kidney health. Citrate in the urine helps prevent the formation of kidney stones, particularly calcium-based stones, by binding to calcium and reducing its availability to form crystals. The objective of this study was to evaluate the performance characteristics of BEN Biomedical Enterprise citric acid quantitative assay configured on a Roche cobas c503. The validation followed Clinical Laboratory Standards Institute (CLSI) recommendations. Methods Assay parameters were obtained from reagent instructions for use recommendations where available (BEN Biomedical Enterprise, REF: CI8820) and adjusted according to c503 instrument specifications. Reagent preparation was modified to minimize the wastage due to dead volume requirements on the Roche cobas development channel cartridges (Cat No. 08463140190). The assay parameters were configured using the Roche cobas development channel file creator software. Precision was evaluated by running 3 replicates of 2 quality controls (QC) daily across 5 days. Correlation studies were performed by comparing Roche cobas c503 results to Roche cobas c502 (N=40) using patient urine samples. Linearity was assessed using a series of samples made via mixing of a low and high patient pool that spanned the analytical measuring range. All patient samples were deidentified. Result Precision studies demonstrated acceptable performance with coefficient of variations of 5.34% and 1.86% for the low and high QC respectively. Correlation between the Roche cobas c502 and c503 was excellent (r=0.992, slope=1.06, intercept= -0.13 mmol/L). Linearity studies demonstrated a linear assay over a measured range of 0.04 – 12 mmol/L. Conclusion The BEN Biomedical Enterprise urine citric acid kit, configured on a Roche cobas c503, showed a robust performance and was found to be acceptable for use of patient testing.