A Single-Blood-Sample Method Using Inulin for Estimating Feline Glomerular Filtration Rate

Background Application of a multisample method using inulin to estimate glomerular filtration rate (GFR) in cats is cumbersome. Objectives To establish a simplified procedure to estimate GFR in cats, a single‐blood‐sample method using inulin was compared with a conventional 3‐sample method. Animals Nine cats including 6 clinically healthy cats and 3 cats with spontaneous chronic kidney disease. Methods Retrospective study. Inulin was administered as an intravenous bolus at 50 mg/kg to cats, and blood was collected at 60, 90, and 120 minutes later for the 3‐sample method. Serum inulin concentrations were colorimetrically determined by an autoanalyzer method. The GFR in the single‐blood‐sample method was calculated from the dose injected, serum concentration, sampling time, and estimated volume of distribution on the basis of the data of the 3‐sample method. Results An excellent correlation was observed (r = 0.99, P = .0001) between GFR values estimated by the single‐blood‐sample and 3‐sample methods. Conclusions and Clinical Importance The single‐blood‐sample method using inulin provides a practicable and ethical alternative for estimating glomerular filtration rate in cats.