In COVID-19, biomarkers of AKI such as functional biomarkers (cystatin c), damage biomarkers (kidney molecule injury 1: KIM-1, l-type fatty acid binding protein: L-FABP, interleukin 18: IL-18, soluble urokinase-type plasminogen activator receptor: suPAR, and neutrophil gelatinase associated lipocalin: NGAL), and stress biomarkers (tissue inhibitor of metalloproteinase 2: TIMP-2 and insuline-like grow factor binding protein 7: IGFBP7) have been shown to be effective in detecting AKI [34,35]. Here, CST3 is linked to acute kidney injury.