A Study Comparing Values of Serum Potassium Estimated by Colorimetric KIT Method with those Obtained by Direct and Indirect ION Selective Electrode Methods
Kusuma KS, Vanitha Gowda MN, Vasudha KC, Radhika K
Bland Altman analysis, Colorimetry, Direct ISE, Indirect ISE, Potassium, Regression, Simple linear
Citation Information :
KS K, MN VG, KC V, K R. A Study Comparing Values of Serum Potassium Estimated by Colorimetric KIT Method with those Obtained by Direct and Indirect ION Selective Electrode Methods. Indian J Med Biochem 2019; 23 (1):221-225.
Introduction: Electrolyte abnormalities are treatable, but known to cause significant morbidity and mortality amongst the general population seeking health care services. The instruments with Ion selective electrode (ISE) (direct or indirect ISE) are the reference methods which are unavailable in rural health care facilities.
Materials and methods: A prospective study was undertaken with 120 serum samples. Potassium was estimated using direct, indirect ion-selective electrodes ISE and colorimeter. Statistical analysis was done using statistical package for social sciences (SPSS) version 17, NCSS 11 and MINITAB 18 software. A p < 0.05 was considered statistically significant.
Results: A strongly positive correlation for potassium values between the instruments was noted. A simple linear regression analysis was done and a regression equation was derived for potassium values while comparing between the instruments. The Bland Altman analysis with 95% Limits of agreement was computed for potassium values between the instruments. It was well within the CLIA suggested target value ± 0.5 mmol/L for potassium.
Conclusion: The values of potassium estimated on the colorimeter are comparable with direct and indirect ISE in all the ranges. The derived regression equation calculates a predicted value for direct and indirect ISE using the values obtained on the colorimeter. This will be beneficial in identifying the altered levels of potassium in patients attending the peripheral health centers, use appropriate intervention and thereby reduce the morbidity and mortality with the use of a cost-effective and logistically feasible instrument viz., colorimeter.
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