MEASURING ELECTROLYTES - AN EVALUATION OF THE IDEXX VETLYTE ION-SELECTIVE ELECTRODE METHOD

This study was conducted using more than 100 samples from three animal species (dog, cat and horse) to examine the differences in plasma sod ium (Na), potassium (K) and chloride (Cl) readings made by the IDEXX V etlyte ion selective electrode (ISE) methodology compared to flame pho tometry and chloridometry. The ISE measurements were significantly hig her (P<0.001) by an average of 5.7%. The average differences were: Na, 8.2mmol/l K, 0.2lmmol/l and Cl, 6.9mmol/l. K values were most highly correlated by both methods in all species, and Cl in the horse showed the lowest correlation. Na values in the dog were better correlated th an in the horse and cat. The precision of the ISE was acceptable, but with Na measurements showing more variation on the ISE than the flame photometer in between-run analyses. Reference ranges were determined f or the ISE and were found to be higher than those available from the m anufacturer for most electrolytes in the dog and cat, but the ranges w ere narrower for the horse. The presence of lipaemia in four plasma sa mples resulted in lower than average values for Na and Cl, but not K, when compared to nonlipaemic samples.