CST3 and acute kidney injury: Considering the limitations of currently used markers, which are increased after significant kidney damage, alternative functional and damage biomarkers of AKI, such as Cystatin C (Cys-C), Neutrophil Gelatinase-Associated Lipocalin (NGAL), Human-Kidney Injury Molecule-1 (KIM-1), Interleukin-18 (IL-18), Tissue inhibitor metalloproteinase 2 (TIMP-2) and Insulin-like Growth Factor Binding Protein 7 (IGFBP7), urinary calprotectin, Retinol binding protein (URPB4), Liver-type fatty acid binding protein (L-FABP), and clusterin, were evaluated.