Comparison of whole blood and plasma potassium concentrations in dogs using the Reflovet system.
BACKGROUND
The Reflovet system is designed for chemical analysis of whole blood. However, plasma or serum is recommended for potassium analysis because of possible interference from RBC potassium. Because RBC potassium concentration is low in most canine erythrocytes, however, there should be little or no interference.


OBJECTIVE
The objective of this study was to compare potassium results obtained in whole blood and in plasma from dogs using the Reflovet system.


METHODS
Blood samples were collected from 104 dogs into lithium-heparin tubes. The potassium concentration was measured in whole blood, and subsequently the PCV was measured. Samples were centrifuged and the potassium concentration was measured in plasma. Comparisons were made using Deming's regression and Bland-Altman difference plots.


RESULTS
There was very good correlation between results of potassium measurements in whole blood and plasma (r = 0.93). Potassium values were moderately lower in whole blood: Potassium(blood) = 0.912 x Potassium(plasma)+ 0.119. Hemolysis had a negligible effect on the results, but the difference increased with the PCV value. In more than 90% of samples, the difference between the 2 measurements was <or= 0.3 mmol/L.


CONCLUSIONS
There is only a negligible difference in most cases between potassium values in canine plasma and whole blood using the Reflovet system.
Trumel
C
C
Department of Companion Animal Medicine, National Veterinary School, Toulouse, France.
Verwaerde
P
P
Rascol
A
A
Braun
J P
JP
D000818:Animals; D000925:Anticoagulants / Q000494:pharmacology; D001774:Blood Chemical Analysis / Q000379:methods / Q000662:veterinary*; D001800:Blood Specimen Collection / Q000379:methods / Q000662:veterinary*; D004285:Dogs / Q000097:blood*; D004912:Erythrocytes / Q000737:chemistry; D006461:Hemolysis; D006493:Heparin / Q000494:pharmacology; D010949:Plasma / Q000737:chemistry; D011188:Potassium / Q000032:analysis / Q000097:blood*; D012680:Sensitivity and Specificity
D000925:Anticoagulants; D006493:Heparin; D011188:Potassium