Besides underestimating the true change in GFR, the increase in serum creatinine after CM exposure is delayed achieving a maximum two to five days after CM exposure as compared to cystatin C, a more sensitive marker, which was shown to rise earlier, to peak as early as 24 hours after CM administration, and to detect even subtle changes in GFR after acute kidney injury including CIN [19,26-30]. This evidence concerns the gene CST3 and acute kidney injury.