Multicenter evaluation of the ProNephro AKI™ assay performance and stability in pediatric patients

Acute Kidney Injury (AKI), defined by increased serum creatinine or decreased urine volume, is highly prevalent in critically ill pediatric patients. Reliance on these for AKI diagnosis is unreliable due to inaccuracy and delayed response. Neutrophil Gelatinase-Associated Lipocalin (NGAL) is a promising biomarker for early AKI detection. This study investigated the analytical performance of a new automated urine NGAL test in pediatric patients.

The ProNephroAKI™ particle-enhanced turbidimetric immunoassay was run on the Roche cobas® c501 analyzer to measure urine NGAL in pediatric patients. The test sensitivity, specificity, and linearity were evaluated. The test reproducibility was studied in three laboratories using seven pediatric urine samples. The stability of urine NGAL was assessed in sixteen native urine pediatric samples after storage at room temperature, refrigerated, and frozen.

The limits of blank (LoB), detection (LoD), and quantitation (LoQ) were determined as 9, 14, and 18 ng/mL, respectively. Linearity was confirmed across the range of 50-3000 ng/mL. Precision studies following CLSI EP5-03 guidelines showed coefficients of variation (CVs) for repeatability, between-run, between-day, and total precision at ≤5.0 %, ≤3.1 %, ≤1.7 %, and ≤4.9 %, respectively. Reproducibility across three laboratories was ≤6.6 %. Specificity tests showed no significant interference from high specific gravity, 15 endogenous substances, 3 contrast agents, pH variations (3.3-10.3), or 33 pharmaceutical compounds, except very high concentrations of cefepime and ceftriaxone. Cross-reactivity was not observed from 10 potential cross-reactive biomarkers. NGAL stability in urine was tested with samples from 16 patients, demonstrating stability for 2 days at ambient temperature, 4 days refrigerated, 13 months frozen (-70 °C or below), and 3 freeze/thaw cycles.

The ProNephroAKI™ assay shows excellent precision, reproducibility, sensitivity, specificity, and stability, meeting the required analytical performance for clinical use in diagnosing and managing AKI in critically ill pediatric patients.