 Patients aged 18 years or older undergoing planed PCI at the institution of first affiliated hospital of SYSU were prospectively recruited between May 2014 and July 2015. The exclusion criteria were pregnancy, lactation, sepsis, the intravascular administration of a contrast medium within the past 7 days, nephroprotective drug treatment e.g., N-acetylcysteine, theophylline, sodium bicarbonate, prostaglandin E1, nephrotoxic drug intake e.g., non-steroidal anti-inflammatory drugs, metformin, aminoglycosides, cisplatin within the past 7 days, a history of serious allergic to contrast media, renal transplantation, end-stage renal disease necessitating dialysis, and severe concomitant disease of other systems. 