Evaluation of an electrolyte analyser for measurement of concentrations of ionized calcium and magnesium in cats

The goal of this study was to evaluate the Nova CRT 8 electrolyte analyser for determination of concentrations of ionized calcium (Ca-i) and magnesium (Mg-i) in cats, to determine the effects of sample handling and storage and to establish reference ranges. The precision and analytical accuracy of the Nova CRT 8 analyser were good. The concentrations of Cai and Mgi were significantly lower in aerobically handled serum samples than in those handled anaerobically. The concentrations of Ca-i and Mg-i differed significantly among whole blood, plasma and serum. In anaerobically handled serum, the concentration of Cai was stable for 8 It at 22 degrees C, for 5 days at 4 degrees C and for 1 week at -20 degrees C. The concentration of Mg-i was stable for 4 h at 22 degrees C but for less than 24 h at 4 degrees C and for less than 1 week at -20 degrees C, In serum from 36 cats, the reference ranges were 1.20-1.35 mmol/L for Ca-i and 0.47-0.59 mmol/L for Mg-i. The Nova CRT 8 electrolyte analyser is suitable for determination of Cai and Mg-i concentrations in cats. Anaerobically handled serum samples are recommended and, stored at room temperature, they yield accurate results when analysed within 4 h.