Objective: To compare results of biochemical analyses performed on plasma samples obtained from healthy dogs and cats by use of standard and microsample blood collection tubes.
Design: Evaluation study.
Animals: 29 healthy client-owned animals (14 dogs and 15 cats).
Procedures: A blood sample (3 mL) was collected from each animal; 2.5 mL was transferred into a vacuum tube that contained lithium heparin, and 0.5 mL was transferred into a microsample tube that contained lithium heparin. Variables evaluated were albumin, bicarbonate, BUN, calcium, chloride, cholesterol, creatinine, glucose, phosphorus, potassium, sodium, total bilirubin, and total protein concentrations and alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, and creatine kinase activities. Results for the 2 types of tubes in each species were compared by use of Pearson correlation coefficients, Passing-Bablok regression analysis, and Bland-Altman analysis.
Results: Data were normally distributed, except for creatine kinase activity of cats. The Pearson correlation coefficient was minimal for total bilirubin concentration in cats and moderate, high, or very high for all other variables. Constant bias for cholesterol and glucose concentration in dogs was identified during Bland-Altman analysis, although the mean difference between types of blood collection tubes was small. No constant or proportional bias for any other variable was revealed by regression analysis or Bland-Altman analysis.
Conclusions and clinical relevance: Samples obtained from healthy dogs and cats by use of microsample blood collection tubes that contained lithium heparin provided clinically equivalent biochemical results, compared with results for samples obtained by use of standard blood collection tubes, and minimized the total sample volume collected for diagnostic testing.