Estimates of biologic variation in specific feline pancreatic lipase concentrations in cats without clinical or ultrasonographic evidence of pancreatitis

Background: Serum concentrations of feline-specific pancreatic lipase are commonly used for diagnosis and monitoring of pancreatitis in cats, but little is known regarding biologic variation of this analyte. Objectives: The purpose of the study was to determine biologic variation, index of individuality, and reference change values (RCV) for specific feline pancreatic lipase concentrations (Spec fPL) in apparently healthy cats. Methods: Four blood samples were collected prospectively from 12 apparently healthy cats at 2-week intervals. The Spec fPL was measured in all serum samples by a reference laboratory. Results: Intra-individual variation for Spec fPL was 33.5% (95% CI 27.1–43.8%); inter-individual variation was 99.9% (69.2–169.9%) and analytic variation was 7.3% (6.1–9.2%). Reciprocal index of individuality for Spec fPL was 2.9 (2.5–3.8), the 2-sided RCV was 95.1% (77.0–123.9%). Conclusions: Due to high individuality, use of a population-based RI for Spec fPL may fail to detect clinically significant elevations in individual cats. The use of subject-based RIs for Spec fPL may have greater sensitivity for the detection of a change in pancreatic physiology in cats; however, this would require serial assessment of apparently healthy cats.