Comparison of the Results of Venous Blood Gas and Laboratory Measurement of Potassium

Objective: To compare venous blood gas potassium levels, which provides rapid results, with laboratory potassium levels. Material and Methods: We reviewed the data of patients who had been referred to our emergency service between January 1 2011 and March 21 2011. Concurrent venous blood gas potassium levels and laboratory potassium levels from 99 patients were included. The data were analyzed using SPSS for Windows version 9.0.Results: Laboratory potassium levels were found to be 4.5 mmol/l (SD 0.86 mmol/l, 95% CI 4.32-4.66 mmol/l, min. 3.1 mmol/l, max. 7.3 mmol/l). Venous blood gas potassium levels were found to be 3.94 mmol/l (SD 0.79 mmol/l, 95% CI 3.78-4.09 mmol/l, min. 2.25 mmol/l, max. 6.37 mmol/l). The difference between laboratory potassium levels and venous blood gas potassium levels was 0.56 mmol/l (SD 0.41 mmol/l, 95% limits of agreement were from -0.24 mmol/l to 1.36 mmol/l, 95% CI 0.48-0.64 mmol/l). Both potassium levels were highly correlated (r= 0.882, p<0.001). Laboratory potassium levels were higher than venous blood gas potassium levels in 97% of patients.Conclusion: In this study, laboratory potassium levels were found to be higher than venous blood gas potassium levels. According to these results, venous blood gas potassium levels cannot be used in place of laboratory potassium levels. However, in emergency services, blood gas potassium levels may be used for especially critical patients until laboratory potassium levels are obtained. Further investigations are needed on this topic.