Bicarbonate measurements are used in the diagnosis and treatment of numerous potentially serious disorders associated with changes in body acid-base balance. The determination of bicarbonate (CO2) is used in conjunction with other clinical and laboratory information for the evaluation of acid-base status. An elevation of the CO2 level may be observed in compensated respiratory acidosis and metabolic alkalosis. Low CO2 levels may be observed in compensated respiratory alkalosis and metabolic acidosis.1 Additional laboratory determinations will permit differentiation between metabolic and respiratory conditions.