Measurement of Renal Function with Iohexol

A Comparison of Iohexol, ^99mTc-DTPA, and ⁵¹Cr-EDTA Clearance

Abstract

The nonionic iodinated contrast medium, iohexol, introduced for clinical urography, is eliminated from the human organism mainly by glomerular filtration. The aim of this study was to analyze the applicability of iohexol for glomerular filtration rate (GFR) measurement by comparing the plasma clearance of iohexol to the plasma clearance of the traditionally employed substances, chromium-51-EDTA and technetium-99m-DTPA. Iohexol concentration was measured by x-ray fluorescence. To analyze for possible acute effect of iohexol on renal function, additional measurements of ^99mTc-DTPA clearance were made prior to the injection of iohexol. In 15 patients having clearance values between 30 and 130 ml/min per 1.73 m², there were close correlations (r=0.95-0.98) among iohexol, ⁵¹Cr-EDTA, and ^99mTc-DTPA clearance. No significant acute renal effect of iohexol was demonstrated. It is concluded that measurement of iohexol clearance provides information about GFR that is as valid as measurements of ⁵¹Cr-EDTA and^99mTc-DTPA clearance. Thus, it is possible to perform urography and a determination of GFR using a single injection of iohexol.