Background: Besides flow cytometric detection of cellular hemoglobin (HGB) concentration, the ADVIA 2120 uses a novel cyanide-free colorimetric method to determine extracellular total HGB concentration. In human samples, the results are equivalent to those of the cyanmethemoglobin method on the ADVIA 120. Cyanide-free HGB measurement has not been evaluated in animal samples.
Objectives: The aim of this prospective study was to compare the 3 methods of HGB analysis on the ADVIA 2120 and ADVIA 120 in blood samples from dogs, cats, and horses.
Methods: Consecutive fresh K(3)EDTA blood samples from 119 dogs, 113 cats, and 151 horses submitted to the Central Laboratory, Department of Veterinary Clinical Sciences, Justus-Liebig University Giessen, were included. A CBC was performed on each sample using the ADVIA 2120 and ADVIA 120. Colorimetric and cellular HGB concentrations and all calculated variables based on HGB measurement were compared using linear regression, Passing Bablok regression, and Bland Altman plots, using the ADVIA 120 as the reference method.
Results: In samples from all species, an excellent correlation was found for colorimetric HGB results (r=0.99). HGB measured with the cyanide-free method was overestimated on the ADVIA 2120 compared with the cyanide-based method on the ADVIA 120, with a mean proportional bias of -21.0% (dog), -22.0% (cat), and -19.4% (horse). The correlation of cellular HGB concentration between analyzers was excellent (r=0.99); however, imprecision was higher than for colorimetric methods. Excellent to fair agreement was found for all calculated variables.
Conclusion: The cyanide-free method of HGB determination is appropriate for use in blood samples from animals, provided the proportional bias is considered.