Acute kidney injury (AKI) is an infrequent but major and well - recognized complication of cardiac surgery (1, 2). Its incidence ranges from 1 to 30% (3). Numerous pre-, intra-, and postoperative factors have been associated with the development of AKI after cardiac surgery (3-19). Most commonly used definitions are the absolute serum creatinine level, its change within one week and/or the need for dialysis in previously undialysed patients (1, 3-5, 9-11, 19-25). In patients who are older, more obese with Type 2 diabetes and hypertension, there is increasing interest in the effects of chronic kidney disease on the cardiovascular system (26). Recent studies demonstrated that even minimal increases in serum creatinine are associated with a rising risk of mortality, hospital length of stay, and cost (27, 28). The Acute Dialysis Quality Initiative Group standardized with their Risk, Injury, Failure, Loss of Kidney Function, End-Stage Kidney Disease criteria and their modifications to the Acute Kidney Injury Network criteria the definitions of AKI (19, 29, 30). Both criteria need a baseline serum creatinine value for estimation (31).