Base excess - arterial blood

Last updated: Saturday, 13, March, 2004

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Item Process

1 mL arterial blood collected anaerobically in a heparinised syringe (sufficient for oxygen, carbon dioxide, pH measurements) and transported rapidly to the laboratory in a capped syringe with needle removed.


Derived parameter from pH, pCO2 and haemoglobin measurements; calculated routinely with blood gas analysis.

Reference Interval

(-3) to (+3) mmol/L.


Assessment of the metabolic component of acid-base disorders.


Base excess is increased in metabolic alkalosis (primary or secondary to respiratory acidosis) and is decreased in metabolic acidosis (primary or secondary to respiratory alkalosis).


Siggaard-Andersen O. Scand J Clin Lab Invest 1971; 27: 239-245.