Most of the CO2 is in the form of a substance called bicarbonate (HCO3-). Therefore, the CO2 blood test is really a measure of your blood bicarbonate level. More...

Collaboration diagram for CO2:

Most of the CO2 is in the form of a substance called bicarbonate (HCO3-). Therefore, the CO2 blood test is really a measure of your blood bicarbonate level.