LCN2 and acute kidney injury: Searches were performed in PubMed, Scopus, and Web of Science using combinations of keywords such as “cardiorenal syndrome,” “biomarkers,” “heart failure,” “acute kidney injury,” “chronic kidney disease,” and specific marker names (e.g., NGAL, KIM-1, cystatin C, CA125, bio-ADM, FGF-23, etc.).