Commutability and interchangeability of commercial quality control materials with feline plasma for common biochemical analytes.

Background: Species-specific plasma or serum pools are considered the ideal standard material for quality control materials (QCM) instead of commercially available human QCM. However, using plasma or serum pools is limited by volume restrictions, degradation over time, and a narrow range of analyte concentrations. Concentrations of QCM analytes should be consistent or commutable with those from species-specific plasma/serum samples, and the precision from plasma pools should be comparable or interchangeable with commercial human QCM.

Objectives: The aims of this study were to determine the commutability and interchangeability of 2 levels of commercial QCM (MAS chemTRAK-H [CT]) with feline plasma pools (PP) from normal and renal disease cats measured using a commercial laboratory analyzer and a veterinary in-house analyzer.

Methods: Agreement between the 2 analyzers was assessed for 16 analytes by correlation and Passing-Bablok regression analyses of feline plasma samples. The difference between each CT data point and the regression line (residuals) was determined and standardized, and CT were considered 'commutable' with PP if the standardized residual was within a range of -3 to 3. Coefficients of variation (CVs) for CT and PP for 16 analytes on 2 analyzers were compared by bootstrap analysis to determine interchangeability.

Results: Most CT analytes were within the range of patient plasma sample analytes, thus commutable. Only 2 analytes had equivalent precision for both levels of CT and both levels of PP, and 5 additional analytes had similar precision for at least one level of CT compared to at least one level of PP.

Conclusions: The QCM assessed is commutable to feline PP within the tested ranges for 2 particular analyzers. Commutability does not grant interchangeability.