OBJECTIVE: To understand the effects of contrast agents on renal function when coronary angiography is performed. METHODS: Changes in renal function were prospectively observed in 141 patients who underwent coronary angiography with nonionic hypotonic contrast agent iodixanol or isotonic contrast agent iodixanol. Blood urea nitrogen (BUN), blood creatinine vSCrw, blood cystatin Cvcystatin C, Cys Cw, urinary microalbumin (mALB), urinary transferrin (TRF), α1-microglobulin (α1-MG), N-acetyl-β-D-aminoglucosidase (NAG), and creatinine. Results: compared with the pre-imaging day, the blood Cys C was significantly elevated vP<0.01w on post-imaging day 1, exceeding the normal range, and the blood Cys C was still higher than the pre-imaging level vP<0.01w on post-imaging day 2, but had decreased to the normal range; compared with the post-imaging day 1, the blood Cys C was significantly decreased vP<0.01w on post-imaging day 2. blood BUN, SCr and electrolytes did not change significantly before and after imaging. There were no significant changes in blood BUN, SCr and electrolytes before and after contrast; mALB, TRF, α1-MG and NAG were significantly increased on day 1 after contrast vP<0.01w, exceeding the normal range, and on day 2 after contrast, NAG was still significantly higher than before contrast P<0.01, α1-MG was still higher than before contrast vP<0.05w, and mALB and TRF returned to pre-contrast levels (P>0.05); compared with day 1 after contrast Compared with day 1 after imaging, mALB decreased significantly on day 2 after imaging vP<0.05w, and TRF, α1-MG and NAG all decreased significantly vP<0.01w. CONCLUSION: In patients without baseline renal insufficiency, no cases of CIN occurred after imaging, and some patients had transient mild proteinuria and elevated urease; age and diabetes mellitus may be the main risk factors affecting the blood Cys C on the first day after imaging The main risk factors for changes in blood Cys C on the first day after imaging may be age and diabetes mellitus.