Differences in Renal Tubular Toxicity of High- and Low-Osmolality Contrast Media

Kazunari Kaneko, Department of Pediatrics, Juntendo University School of Medicine, 2-1-1, Hongo, Bunkyo-KU, Tokyo 113 (Japan) Dear Sir, We read with great interest the article ‘Nephrotoxicity of Highand Low-Osmolality Contrast Media, [1]. In this article, Jevnikar et al. reported that no significant change in glomerular filtration rate was found in any type of contrast media (CM) so the significance of the enzymuria remained uncertain and, therefore, no evidence that the newer CM were less nephrotoxic than the high-osmolal-ity variety could be found. We have also investigated nephrotoxicity including tubular dysfunction of highland low-osmolality CM. Our results were almost similar to those of Jevnikar et al. In addition to urinary excretion of enzyme as an index of tubular injury, urinary excretion of low molecular weight protein, ß2-microglobulin (ß2-MG), was determined to evaluate tubular function in our study. Our subjects, methods and results were as follows (all results are expressed as mean ± SE). Thirty-five patients admitted to our hospital for the purpose of undergoing cardiac angiography were randomized into two groups receiving iopamidol (800 mosm/kg H20) or diatrizoate (2,070 mosm/kg H20). As shown in table 1, there were no significant differences in age and loaded dose of iodine between the two groups. On both the days before and after cardiac angiography, blood sampling and 24-hour urine collecting were performed. Values for creatinine and electrolytes in blood and urine samples were determined by routine method. Serum and urine concentration of ß2-MG were determined by radioimmunoassay, and urinary N-acetyl-ß-D-glucosaminidase (NAG) activity was determined by a spectrophotometric method [2]. In this study, there were no significant changes in both serum creatinine and creatinine clearance following the administration of any of the CM [data not shown, p > 0.05 Table I. CM description