[Urography and renal clearance of contrast media. A randomized comparison of an ionic high-osmolar and a non-ionic...

One hundred patients with confirmed or presumedly normal serum creatinine level had an intravenous urography with either an ionic high-osmolar or an non-ionic low-osmolar contrast medium after randomization. Employing Renalyzer PRX 90, the plasma concentration of iodine were determined on blood samples drawn approximately three and four hours after the injection of the contrast medium. From these, the glomerular filtration rate was calculated. The urograms were assessed blindly as regards nephrographic and pyelographic opacification as well as the overall quality as regards the diagnosis was assessed. The clearance was found to vary between 42 and 125 ml x min-1 x 1.73 m-2. No systematic connection of practical significance was found between the clearance and assessment of the urograms. Considerable variation was found in the clearance among not only the poor but also the good urograms. No demonstrable differences of clinical significance were found between the two contrast media. It is concluded that it is not possible to assess clearance from the appearance of the nephrogram and pyelogram or from the overall diagnostic quality in routine urographies regardless of whether ionic high-osmolar or non-ionic low-osmolar contrast media are employed in patients with normal serum creatinine levels.