Comparison of Plasma/Serum Electrolyte and Metabolite Testing on Blood Gas ABL90 and Core Laboratory Cobas c501...

Core medical laboratory chemistry analyzers typically use plasma or serum for electrolytes (sodium, potassium, chloride) and metabolites (glucose, lactate, total carbon dioxide) testing, whereas blood gas analyzers use whole blood. The aim of this study was to compare electrolyte and metabolite results in plasma or serum sample type using blood gas analyzer ABL90 with those generated by a core laboratory Cobas c501 analyzer.

One plasma separator tube and one serum separator tube were drawn from 53 apparently healthy individuals and outpatients. All samples were run on Roche Cobas c501 and were then run on Radiometer ABL90 analyzers for sodium (Na+), potassium (K+), chloride (Cl-), glucose (Glu), lactate, and total carbon dioxide (tCO2) parameters. Paired measurements between the ABL90 and Cobas c501 were compared, and their differences were assessed for statistical and clinical significance.

Except for serum glucose, to which ABL90 showed no statistical difference (p = 0.226) compared to Cobas c501, ABL90 demonstrated statistical significance (p < 0.05) vs. c501 on all other plasma and serum parameters. However, most parameters on ABL90 differ insignificantly to those on c501, except Na+ and Cl-. ABL90 also demonstrated excellent correlations with c501 in glucose, lactate, K+, and plasma tCO2 (correlation coefficient r ≥ 0.95) and modest correlations in Na+ and Cl- (r between 0.71 - 0.80).

ABL90 blood gas analyzer and c501 chemistry analyzer are comparable when comparing metabolite (glucose, lactate, and plasma tCO2) and electrolyte (K+) values on plasma/serum. Na+ and Cl- plasma/serum testing on ABL90 need further research.