Background Large doses of contrast media (CM) are usually indispensable for percutaneous cardiac interventions.As interventional cardiac procedures are steadily increasing,contrast-induced nephropathy (CIN) has become the third leading cause for hospital acquired AKI.Clinical epidemiology shows that elderly,diabetes and kidney dysfunction are recognized as important risk factor of CIN.But there is still lack of large sample research to explore the therapy to prevent CIN in this part of patients at present.