Interpretation
In the absence of a blood gas profile, the plasma bicarbonate can only give an approximation of the acid-base status.
A low plasma bicarbonate may suggest the presence of a metabolic acidosis or (more rarely) metabolic compensation for a chronic respiratory alkalosis. Another common cause of a low bicarbonate is an old specimen which has been uncapped, due to loss of bicarbonate from the specimen (as CO2) to the ambient atmosphere.
A high plasma bicarbonate may be due to a metabolic alkalosis or metabolic compensation for a chronic respiratory acidosis.
Bicarbonate is part of the anion gap calculation.
Test Method
Bicarbonate is measured by enzymatic reaction with malate dehydrogenase and measures a decrease in absorbance. This method uses Beckman Coulter reagents.