Interpretation
In general, the chloride concentration tracks the sodium concentration. Large discrepancies between sodium and chloride often indicate specimen contamination (for example, contamination with the sodium salt of a drug left in an IV line).
The chloride result is part of the anion gap calculation, which is used to narrow down the causes of a metabolic acidosis. Hyperchloraemia is associated with a normal anion gap metabolic acidosis (i.e. chloride retention to compensate for loss of bicarbonate).
In patients with severe hyperproteinaemia or hyperlipidaemia, blood gas chloride (and sodium) results should be used in preference to those from a laboratory analyser, as laboratory results may be falsely low.
Test Method
Indirect ion specific electrode (ISE) performed on Beckman Coulter AU5822 analysers.