LCN2 and kidney disorder: Postoperative acute kidney injury (AKI) is a common occurrence in pediatric cardiac surgery, with reported incidences ranging from 3.4%1 to 86%.2 Although various classification systems have been used in the diagnosis of AKI, the Kidney Disease Improving Global Outcomes (KDIGO) classification is now regarded as the standard diagnostic classification tool.3 Biomarkers such as Kidney Injury Molecule-1 (KIM-1) and Neutrophil Gelatinase-Associated Lipocalin (NGAL) have shown a higher sensitivity to detect more subtle forms of renal injury,4 but are still mostly used in research settings.5