USE OF PLASMA-CLEARANCE OF INULIN FOR ESTIMATING GLOMERULAR-FILTRATION RATE IN CATS

Objective-To evaluate utility of a method for estimating glomerular fi ltration rate after a single IV injection of inulin. Animals-Cats that were renal intact (n = 3) or had renal mass reduced by partial nephre ctomy (n = 6). Procedure-Plasma clearance of inulin (PCln) was taken a s the quotient of the administered dose of inulin (150 mg) divided by the area under the plasma inulin concentration versus time curve deter mined by 3 methods (PCln(1)-PCln(3)). Results for PCln were compared w ith simultaneously obtained values for urinary clearance of exogenous creatinine (CCr), an accepted method for the estimation of glomerular filtration rate (GFR) in cats. Results-Values for PCln were closely re lated (R(2) ranged from 0.951 to 0.972, P < 0.0001 in all instances) t o CCr. However, PCln(3) provided an estimate of GFR that consistently overestimated CCr. Conclusion-Determination of PCln by use of PCln(1) and PCln(2) provided a reliable estimate of GFR in cats of this study. Clinical Relevance-Determination of PCln appears to provide a reliabl e estimate of GFR in cats with early-stage renal disease and no eviden ce of derangement of body fluid status. In particular, PCln(2), which requires only 3 determinations of plasma inulin concentration, should be considered when an estimate of GFR is sought in a cat with suspecte d early-stage renal disease.