<qa>  What is the most frequently defined as an increase in serum creatinine?The prevention and early intervention of CIN has been hampered mainly by the lack of a consensus definition and the paucity of early predictive biomarkers to accurately identify high-risk patients. CIN is most frequently defined as an increase in serum creatinine sCr by 25-50 above the baseline, generally occurring within the first 24 h after contrast exposure, in the absence of other causes. However, sCr is an unreliable indicator during acute changes in kidney function, and alterations in sCr levels are not particularly sensitive or specific for small changes in the glomerular filtration rate GFRe, gender, race and intravascular volume. Biomarkers such as kidney injury molecule-1 KIM-1 and neutrophil gelatinase-associated lipocalin NGAL have been used for the early diagnosis of AKI, although with no definitive results. 