Experimental studies comparing iohexol and 51Cr-EDTA for glomerular filtration rate measurements

The total plasma clearance as well as the renal clearance of iohexol were evaluated for determination of the glomerular filtration rate (GFR) in 16 anesthetized pigs. The iohexol levels in urine and plasma were measured by X-ray fluorescence. The total plasma clearance of 1 and 4 ml/kg b.w. of iohexol 300 mg I/ml was compared to the simultaneously as well as nonsimultaneously calculated total plasma clearance of 51Cr-EDTA. The total plasma clearance of 51Cr-EDTA and of iohexol turned out to be equal and independent of the injected dose of iohexol. The injected dose did not have any effect on the renal clearance of iohexol either. It is concluded that iohexol and 51Cr-EDTA are similar as marker substances for determination of the GFR.