Abstract: OBJECTIVE To study the metabolic characteristics of endogenous metabolites in urine of patients with renal tubular function impairment after coronary angiography using iodixanol and to analyze the potential mechanism of renal tubular damage caused by iodixanol. METHODS Patients with normal renal tubular function and with renal tubular function injury after 24 h of coronary angiography with iodixanol were divided into the normal group(n=50) and the injured group(n=50), their morning urine samples were collected 24 h after angiography. The urine samples were metabolically analyzed using ultra high performance liquid chromatography-mass spectrometry combined with orthogonal partial least squares(OPLS-DA), and the metabolic characteristics of renal tubule function injured by iodoxazole were searched by Metlin, HMDB, KEGG and MetaboAnalyst databases. RESULTS The 25 metabolites(variable important in projection, VIP)>1 related to the renal tubular function damage by iodixanol were identified, and the content of 3 metabolites with metabolic differences significantly decreased(VIP>1, P<0.05), which were L-phenylalanine, L-tyrosine and L-tryptophan respectively. There were 9 metabolic pathways involved in 25 different metabolites, mainly amino acid metabolism. Among them, there were 2 target metabolic pathways(Impact>0.10, P<0.05), which were phenylalanine, tyrosine and tryptophan biosynthesis and phenylalanine metabolism. CONCLUSION The significant decrease of L-phenylalanine, L-tyrosine and L-tryptophan in urine after coronary angiography with iodixanol may indicate the injury of renal tubular function. The urine metabolism of patients with renal tubular function injury after coronary angiography with iodixanol is mainly manifested as amino acid metabolism disorder, and iodixanol damages renal tubular function mainly by affecting phenylalanine, tyrosine and tryptophan biosynthesis and phenylalanine metabolism.