CST3 and acute kidney injury: To date, many biomarkers for AKI, such as liver‐type fatty acid‐binding protein (L‐FABP), neutrophil gelatinase‐associated lipocalin (NGAL), kidney injury molecule‐1 (KIM‐1), interleukin‐18 (IL‐18), cystatin C, have been developed and are available in clinical care, including early diagnosis of AKI (Alge and Arthur 2015).