Yonsei Med J.  2014 Sep;55(5):1348-1353. 10.3349/ymj.2014.55.5.1348.

Evaluating the Utility of Rapid Point-of-Care Potassium Testing for the Early Identification of Hyperkalemia in Patients with Chronic Kidney Disease in the Emergency Department

• You JS
• Park YS
• Chung HS
• Lee HS
• Joo Y
• Park JW
• Chung SP
• Lee SH
• Lee HS

• KMID: 1799501
• DOI: http://doi.org/10.3349/ymj.2014.55.5.1348

Abstract

PURPOSE
Severe hyperkalemia leads to significant morbidity and mortality if it is not immediately recognized and treated. The concentration of potassium (K+) in the serum increases along with deteriorating renal function. The use of point-of-care K+ (POC-K+) in chronic kidney disease (CKD) could reduce the time for an accurate diagnosis and treatment, saving lives. We hypothesized that POC-K+ would accurately report K+ serum level without significant differences compared to reference testing, regardless of the renal function of the patient.
MATERIALS AND METHODS
The retrospective study was performed between January 2008 and September 2011 at an urban hospital in Seoul. The screening program using POC was conducted as a critical pathway for rapid evaluation and treatment of hyperkalemia since 2008. When a patient with CKD had at least one warning symptom or sign of hyperkalemia, both POC-K+ and routine laboratory tests were simultaneously ordered. The reliability of the two assays for serum-creatinine was assessed by intra-class correlation coefficient (ICC) analysis using absolute agreement of two-way mixed model.
RESULTS
High levels of reliability were found between POC and the laboratory reference tests for K+ (ICC=0.913, 95% CI 0.903-0.922) and between two tests for K+ according to changes in the serum-creatinine levels in CKD patients.
CONCLUSION
The results of POC-K+ correlate well with values obtained from reference laboratory tests and coincide with changes in serum-creatinine of patients with CKD.

Keyword

Point-of-care testing; hyperkalemia; chronic kidney disease

MeSH Terms

Blood Chemical Analysis/methods
Emergency Service, Hospital
Humans
Hyperkalemia/*diagnosis
Point-of-Care Systems
Potassium/*blood
Renal Insufficiency, Chronic/*blood
Reproducibility of Results
Retrospective Studies
Sensitivity and Specificity
Potassium

Figure

• 

  Fig. 1 Box-and-whisker plot. Serum concentrations of potassium detected by POC-K+ and reference tests. Although a significant difference in the mean of 0.39 mmol/L was found between the two groups (p<0.001). The propensity of data for K+ showed a high degree of concordance between POC and the reference test. POC, point-of-care; POCT, point of care testing.

• 

  Fig. 2 Bland-Altman plot showing the mean differences (solid line) and 95% limits of agreement (dot line) for K+ serum levels. POCT, point of care testing.

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  Fig. 3 ROC curves of POC-K+ and reference tests of K+ serum levels. The AUC of POC-K+ can be improved from 82.7 (95% CI 79.9-85.4) to 89.7 (95% CI 87.5-91.9) (p<0.001) if a value of 0.4 mmol/L was added to the mean value result of POC-K+. POC-K+, point-of-care K+; AUC, area under the curve; CI, confidence interval; POCT, point of care testing.

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