Estimation of glomerular filtration rate in dogs by plasma clearance of gadolinium diethylenetriamine pentaacetic acid as measured by use of an ELISA

Abstract

Objective - To evaluate use of gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) to estimate glomerular filtration rate (GFR) by plasma clearance and use of an ELISA as the method of Gd-DTPA quantification. Animals - 16 dogs of various sexes and breeds (12 dogs were clinically normal, and 4 dogs were polyuric and polydipsic with no other clinical or biochemical abnormalities). Procedures - GFR was estimated by measuring the plasma clearance of Gd-DTPA and iohexol by use of an ELISA and high-performance liquid chromatography (HPLC), respectively. The GFR was determined by use of a 1-compartment model for both methods. The GFRs obtained by Gd-DTPA plasma clearance were compared with those obtained by iohexol plasma clearance by use of correlation analysis, paired t tests, and limits of agreement analysis. A paired t test was used to evaluate differences between the 2 plasma clearance methods. Results - A strong linear correlation (r2 = 0.90) was found between GFRs derived from the plasma clearance of Gd-DTPA and those derived from the plasma clearance of iohexol. By use of limits of agreement analysis, almost all (13/14) dogs had Gd-DTPA GFRs that were within 12% of iohexol GFRs. The remaining dog had a Gd-DTPA GFR that was 45% higher than the iohexol GFR. There was no significant difference between Gd-DTPA GFRs and those obtained with iohexol. Conclusions and Clinical Relevance - This study revealed that plasma clearance of Gd-DTPA measured by use of an ELISA is an effective method to estimate GFR in dogs because it compared favorably with results for the iohexol-HPLC method.