Studies conducted in recent years prove it is possible to detect CSA-AKI as soon as 6 h after weaning from cardiopulmonary by-pass (CPB) using urine kidney injury biomarkers, such as neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule 1 (KIM-1), matrix metalloproteinase 9 (MMP-9) and interleukin 18 (IL-18) [6,8,11,12,13,14]. The gene discussed is MMP9; the disease is acute kidney injury.