Discrepancy in Chloride Measurement with Decreasing Bicarbonate Concentrations

Area of Science:

• Clinical Chemistry
• Critical Care Medicine
• Laboratory Diagnostics

Background:

• Accurate serum chloride measurement is vital for managing critically ill patients.
• Electrolyte balance is a key indicator of patient status in intensive care units.

Purpose of the Study:

• To compare chloride concentration measurements obtained from central laboratory analysis and blood gas analysis.
• To identify potential discrepancies in chloride measurements between different methodologies, particularly in specific patient populations.

Main Methods:

• Simultaneous measurement of chloride concentration using two distinct methods: central laboratory (indirect ion-selective electrode) and blood gas analysis (direct ion-selective electrode).
• Comparative analysis of results obtained from both measurement techniques.

Main Results:

• A significant discrepancy in chloride measurement was identified between the central laboratory and blood gas analysis.
• This discrepancy was particularly noted in patients with low serum bicarbonate levels.
• The findings highlight potential issues with indirect ion-selective electrode methodology in specific clinical contexts.

Conclusions:

• Caution is advised when interpreting chloride concentrations derived from indirect ion-selective electrode methods.
• Particular care should be taken in patients presenting with low serum bicarbonate levels.
• Clinical decisions based on chloride levels should consider the measurement methodology employed.