Tubular nephrotoxicity after intravenous urography with ionic high-osmolal and nonionic low-osmolal contrast media in patients with chronic renal insufficiency.

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 gamma-glutamyl transpeptidase, gamma-GT) and of a lysosomal enzyme (N-acetyl-beta 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 gamma-GT excretion increased significantly (p less than 0.01) after diatrizoate. After iopamidol, only gamma-GT excretion increased significantly (p less than 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 gamma-GT are sensitive markers for this toxicity.