Comparison of bicarbonate values from venous blood gas and chemistry panels measured at the time of diagnosis and resolution of diabetes ketoacidosis

OBJECTIVE: To determine if bicarbonate values from venous blood gas (VBG) and plasma chemistry samples provided agreement in determining the bicarbonate criteria for the diagnosis and/or resolution of diabetic ketoacidosis (DKA). METHODS: A retrospective chart review of data from patients admitted to a tertiary care hospital with a diagnosis of DKA over a four year period was performed. Paired bicarbonate values from a VBG and chemistry panel, if drawn within 60 minutes of each other, were compared. RESULTS: At the time of diagnosis of DKA, 197 paired bicarbonate values were available for analysis with the mean difference between the two methods of testing of 2.5 mmol/L. 16 of the 197 (8%) paired values were discordant in meeting criteria for diagnosis of DKA. At the time of resolution of DKA, 83 paired bicarbonate samples were compared. The mean difference was 2.3 mmol/L. 20 of the 83 (24%) paired bicarbonate values showed discordance with regards to meeting the bicarbonate criteria for resolution of DKA. CONCLUSION: Discordance between bicarbonate results from different analysis methods may lead to different determinations as to whether or not a patient meets the biochemical definition for diagnosis and resolution of DKA.