Comparison of Measurements of Glomerular Filtration Rate Using Single-injection Inulin Methods and Urinary Creatinine Clearance in Dogs with Reduced Renal Blood Flow

The purpose of this study was to evaluate the validity of the single injection of inulin (PCIn) compared with standard exogenous creatinine clearance (CCr) in dogs with renal artery stenosis. Two methods for evaluating glomerular filtration rate (GFR), after single bolus intravenous administration of inulin, were assessed in 15 dogs with renal artery stenosis to reduce blood flow ranging from 30% to 80%. The first method was calculated by determination of plasma clearance of inulin using the quotient of the administered dose of inulin (1 g) divided by the area under the plasma inulin concentration vs. time curve (PCIn1) while the second method was calculated using a two-compartment model (PCIn2). The relationship between CCr and the plasma concentration of inulin 75 minutes (C75) after single bolus intravenous administration of inulin was also determined. Results indicated a significant correlation between either of PCIn1, PCIn2 or C75 with conventional CCr. These results support the evaluation of GFR by using PCIn and plasma inulin concentration values in dogs with acutely reduced renal blood flow.