Comparability Assessment of Serum Electrolytes on Different Autoanalysers Working on the Same Principle

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Comparability Assessment of Serum Electrolytes on Different Autoanalysers Working on the Same Principle

Journal Title: National Journal of Laboratory Medicine - Year 2019, Vol 8, Issue 2

Abstract

ABSTRACT Introduction: Electrolyte measurement of critically ill patients is frequently requested in emergency central laboratory. These are either obtained from Point of Care (POC) electrolyte analysers on urgent basis or processed on the autoanalysers. Accurate and rapid measurement of electrolyte such as sodium and potassium help in development of focused course of treatment. Aim: To compare the results of serum electrolytes measured on four different autoanalysers working on the same principle of direct Ion Selective Electrode (ISE) measurement, to determine the extent of agreement amongst them. Materials and Methods: This prospective comparative study was done using 200 patient samples obtained from the Central Biochemistry Laboratory of Lok Nayak Hospital, New Delhi, India. Serum samples were analysed on four different analysers for electrolytes (Na+ and K+), two Roche AVL electrolyte analysers and two Randox Imola autoanalysers working on the same methodology of direct ISE measurement. Means, standard deviations and coefficient of variations were calculated. The Bland-Altman plots were used to compare the results of two different assays and to quantify the limit of agreement. The p-value <0.05 was considered statistically significant. Results: The mean value for sodium was 135±10.6 mmol/L and 136±10.4 mmol/L for Roche AVL 1 and 2 electrolyte analysers; 140±10.9 mmol/L and 140±10.7 mmol/L for Randox Imola 1 and 2 autoanalysers. Similarly, the mean value for potassium were 4.53±2.86 mmol/L, 4.32±1.03 mmol/L, 4.33±0.97 mmol/L and 4.35±0.94 mmol/L for AVL 1, AVL 2, Imola 1 and Imola 2, respectively. The Bland-Altman plots have shown a good agreement of -0.34 to 0.31 for serum potassium for Imola 1 and AVL 1 however, no such agreement was found for sodium values on inter-analyser comparison. The Bland-Altman plots were used to compare the results of two different assays and to quantify the limit of agreement. The p-value of <0.05 was considered statistically significant. Conclusion: Serum electrolytes obtained from electrolyte analysers and autoanalysers showed equivalent results for potassium but not for sodium values. Therefore, potassium values can be used interchangeably from these analysers for making critical decisions but same cannot be concluded for the sodium values. The comparability will be useful to minimize analytical bias and allow the results to be used interchangeably. Obtaining equivalent, rapid and reliable results from ready back-up systems will prove to be time-saving and economical in emergency cases irrespective of the analytical system being used.

Authors and Affiliations

Rashmi Gulia, Binita Goswami

Keywords

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EP ID EP610025
DOI 10.7860/NJLM/2019/40678:2354
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