CI-AKI incidence 72 hours after exposure to contrast medium was 51.4 % ( 257/500 ) , measured as serum creatinine > ( baseline +0.3 mg/dL ) and/or serum cystatin C > ( 1.1 baseline ) , and 7.6 % ( 38/500 ) , measured as both serum creatinine and serum cystatin C > ( baseline +0.3 mg/dL ) or > ( 1.25 baseline ) .