Indian journal of Medical Biochemistry

Register      Login

VOLUME 23 , ISSUE 1 ( January-April, 2019 ) > List of Articles


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

Keywords : Colorimetry, Direct ISE, Indirect ISE, Potassium, Regression, Simple linear,Bland Altman analysis

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.

DOI: 10.5005/jp-journals-10054-0090

License: CC BY-NC 4.0

Published Online: 00-04-2019

Copyright Statement:  Copyright © 2019; Jaypee Brothers Medical Publishers (P) Ltd.


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.

PDF Share
  1. Richardson RW. Sodium and Potassium, Chapter V, Handbook of Non-pathologic variations in blood constituents. CRC Press 1994: 67-80
  2. Sunderman FW Jr, Sunderman FW. The rapid colorimetric estimation of Potassium. Am J Clin Path 1959;29:95.
  3. Sharmaa B and Sarmah D, A comparative evaluation of sodium and potassium measurement by Flame photometer and Direct ISE methods. International Journal of Health Sciences and Research 2013;3(6)59-65.
  4. Breh F, Gaebler OH. The determination of potassium in blood serum. J Biol Chem 1930,87:81-89.
  5. Burnett RW, Covington AK, Fogh-Andersen N, et al. Recommendations for measurement of and convention for reporting sodium and potassium by Ion Selective Electrodes in undiluted serum, plasma or whole blood. International Federation of Clinical Chemistry and Laboratory Medicine (IFCC). IFCC Scientific Division working group on selective electrodes. ClinChem Lab Med Oct 2000;38(10): 1065-1071.
  6. Owierdu WKBA, Dzandu P, Amidu N. Comparison of Ion Selective Electrode, flame emission spectrophotometry and the colorimetric method in the determination of serum electrolytes. Ghana Journal of Allied Health Sciences May 2007:24-30
  7. Albert V, Subramanian A, Rangarajan K, et al. Agreement of two different lab methods used to measure electrolytes. Journal of Lab. Physicians. Jul-Dec 2011;3(2):104-109.
  8. Gupta S, Gupta AK, Singh K, et al. Are sodium and potassium result on arterial blood gas analyzer equivalent to those electrolyte analyzer? Indian J Crit Care Med 2016;20:233-237
  9. Yýlmaz S, Uysal HB, Avcil M, et al. Comparison of different methods for measurement of electrolytes in patients admitted to the ICU. Saudi Med J 2016;37(3)262-267.
  10. Burtis CA, Ashwood ER, Bruns DE, eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics, 4th Edition, St. Louis, MO: Elsevier Saunders. Chapter 27 Electrolyte and Blood Gases 2006:983- 1019.
  11. Dimeski G, Badrick T, St John A. Ion selective electrodes (ISEs) and interferences—a review. Clinica Chimica Acta. 2010 Mar 2;411(5- 6):309-317.
  12. Terri A, Sesin P. Determination of potassium by using sodium tetraphenylboron. Am J Clin Path 1958;29:86-90.
  13. Twomey PJ, Kroll MH. How to make use of linear regression and correlation in quantitative method comparison studies. Int J Clin Pract April 2008;62(4):529-538.
  14. Bishop ML, Fody EP, Schoeff LE, eds, Clinical Chemistry–Principles, Techniques and Correlations. Seventh Edition. Chapter 16, Electrolytes written by George A Harwell, pp. 346-375.
  15. USCLIA 2004. Standards and Certifications: Laboratory requirements (42CFR493). Regulations Part 493. Laboratory Requirements. Subpart I–Proficiency testing programs by specialty and subspecialty, Section 493.931–Routine Chemistry.
  16. Viera AJ, Wouk N. Potassium Disorders: Hypokalemia and Hyperkalemia. Am Fam Physician 2015:92(6):487-495.
PDF Share

© Jaypee Brothers Medical Publishers (P) LTD.