Tubular Nephrotoxicity after Intravenous Urography with Ionic High-Osmolal and Nonionic Low-Osmolal Contrast Media in Patients with Chronic Renal Insufficiency

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Abstract
Nephrotoxicity of intravenous contrast media is more frequent and striking in patients with risk factors, the major one being preexisting chronic renal insufficiency. New nonionic low-osmolal contrast media allegedly have less nephrotoxicity than the traditional ionic high-osmolal ones. This was tested for two contrast media in a group of 18 patients with stable chronic renal insufficiency. The urinary excretion of two brush-border enzymes (alanine aminopeptidase, AAP, and γ-glutamyl transpeptidase, γ-GT) and of a lysosomal enzyme (N-acetyl-β glucosaminidase, NAG), functional markers of tubular injury, were measured before and after intravenous urography with an ionic high-osmolal radiocontrast medium, meglumine sodium diatrizoate, or with a non ionic low-osmolal one, iopamidol. Urinary NAG excretion did not change significantly after administration of either contrast media. Urinary AAP and γ-GT excretion increased significantly (p < 0.01) after diatrizoate. After iopamidol, only γ-GT excretion increased significantly (p < 0.05). Our data suggest that the nonionic low-osmolal radiocontrast medium iopamidol is less toxic to tubules than the ionic high-osmolal medium diatrizoate and that the brush-border enzymes AAP and γ-GT are sensitive markers for this toxicity.