Friedrich et al. examined 81 patients undergoing cardiopulmonary bypass and found that, although NGAL increased after surgery, the peak value neither predict AKI nor the severity of the injury (16); in a similar population Perry et al. found that, although NGAL increases were associated with AKI, however, due to the low sensitivity (38.7%) its evaluation has limited utility (17). This evidence concerns the gene LCN2 and acute kidney injury.