Objective To analyze the clinical significance of four kinds of microalbuminuria detection in early diagnosis of iodinated contrast agent damage to kidney by studying four elements in the patients' urine:microalbumin (mAlb),immunoglobulin G (IgG),α1-microglobulin (α1-MG) and β2-microglobulin (β2-MG).Methods 106 patients who have received percutaneous coronary interventional therapy were chosen and divided into group A(angiography dose ＜ 100ml,n =51) and group B (angiography dose ≥ 100ml,n =55) according to the amount of contrast agent used.Changes in the amount of mAlb,IgG,α1-MG and β2-MG levels,serum creatinine(Scr),endogenous creatinine clearance rate(eGFR) in the urine of the patients before and after the surgery were observed.Results Postoperative α1-MG and β2-MG levels in the urine of group A higher than before surgery (t =-6.748,-11.173,all P ＜0.0 5).2 4 hours after the surgery,mA1b,IgG,α1-MG and β2-MG levels in group B were elevated than before surgery,and the differences were significant(t =-6.223,-3.518,-11.532,-10.773,all P ＜ 0.05).Two groups had significant differences in terms of mAlb,IgG,α1-MG and β2-MG levels after the surgery (F =27.306,4.704,5.118,19.011,all P ＜ 0.05).Conclusion Four kinds of microalbuminuria detecting are conducive to early diagnosis of iodinated contrast agent damage to kidney and assessing the damage degree.The contrast agent damage to kidney first occurs as the renal tubular damage.When the contrast agent was used at a dosage of more than 100ml,glomerular damage occurred.