Objective      To compare the effect of iso-osmolar contrast media with that of low-osmolar contrast media on the renal function of patients with percutaneous coronary intervention (PCI).       Methods      From June 2012 to January 2013

409 inpatients who were diagnosed with coronary artery disease to undergo PCI in Southwest Hospital were enrolled. They were divided into two groups including an iso-osmolar

group (n=195) and a low-osmolar group (n=214). The serum levels of creatinine

urea nitrogen

cystatin C

urea acid and β2-microglobulin and urine levels of β2-microglobulin and microalbumin were assessed before PCI and at 24 and 72 h after PCI to detect incidence of contrast-induced acute kidney injury.       Results      The serum levels of creatinine and β2-microglobulin of the low-osmolar group statistically increased at 24 h after PCI (

P

0.05)

while those of the iso-osmolar group did not change after PCI (

P

0.05). The urine level of β2-microglobulin of the low-osmolar group increased at 24 h after PCI (

P

0.05). The diagnosis of 17 patients (7.94%) in the low-osmolar group and 3 patients (1.54%) in the iso-osmolar group met the criteria of contrast-induced acute kidney injury (CI-AKI)

and the difference between the two groups was statistically significant (

P

0.01). The patients with chronic kidney disease before PCI were all treated with oral and intravenous hyperhydration

and their indicators of renal function did not statistically change after PCI (

P

0.05).       Conclusion      High dose of contrast media can induce CI-AKI

and the incidence of CI-AKI in the low-osmolar group is significantly higher than that in the iso-osmolar group (

P

0.01).