Evaluation of the Roche point of care system for determination of NT-proBNP in urine samples

Introduction: The diagnostic potential of urine NT-pro-BNP has been studied recently and shows great promise, especially for children. Bedside serum-NT-proBNP determination with point of care testing (POCT) is established in adults. This study investigated the analytical capabilities of NT-proBNP POCT measurements for urine-samples. Furthermore, the stability of this biomarker in urine samples at room-temperature was explored.

Methods: 104 urine samples were analysed, partly with double and triple determinations and compared to the established Elecsys system. To investigate the stability of NT-proBNP in urine, five samples were stored at room temperature and analysed 12-hourly over 96 h.

Results: 34 % of samples lay outside the POCT range (60 pg/ml-9000 pg/ml). The 69 values within the range were correlated with those measured by Elecsys (correlation coefficient of 0.92; p < 0.001). Linear regression yields an r² of 0.84. The stability of urine NT-proBNP was shown with correlation coefficients between 0.97 and 1 (p < 0.001).

Conclusion: Analysing NT-ProBNP in urine with cobas h232 POC system is feasible, but the detection range needs to be adjusted. As urine NT-proBNP proved stable for at least 96 h even postal shipping would be possible. Adjusting this system's measuring range could help introduce a new, non-invasive, pain-free parameter.