Bicarbonate Test The Bicarbonate test is used to measure the level of bicarbonate in the blood, which is a buffer that helps maintain the body’s acid-base balance. The test is also called total CO2 test or HCO3 test. Pre-test preparation: No special preparation is usually required for a bicarbonate test. Testing method: A blood sample is taken and sent to a laboratory for analysis. Common symptoms that may prompt a healthcare provider to prescribe a bicarbonate test include:Shortness of breathConfusionFatigueNauseaLoss of appetiteComa Diagnosis:Low levels of bicarbonate in the blood can be a sign of metabolic acidosis, which is a condition in which the body produces too much acid or does not get rid of enough acid.High levels of bicarbonate in the blood can be a sign of metabolic alkalosis, which is a condition in which the body produces too little acid or gets rid of too much acid.