A CO2 blood test measures the amount of carbon dioxide in the liquid part of your blood, called the serum. Carbon dioxide is a waste product produced by the body, and most of it is in the form of bicarbonate, which is a type of electrolyte. Electrolytes are electrically charged minerals that help control the amount of fluid and the balance of acids and bases (pH balance) in your body. A CO2 blood test is often done as part of a group of tests called an electrolyte panel, which may be part of a regular check-up or to diagnose or monitor conditions related to an electrolyte imbalance.
During the test, a healthcare professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out, and the process usually takes less than five minutes. The normal range for CO2 levels in the blood is 23 to 29 milliequivalents per liter (mEq/L) or 23 to 29 millimoles per liter (mmol/L) . Abnormal test results may be a sign that your body is having a hard time keeping the right acid-base balance (pH balance), which may be because of an electrolyte imbalance or certain medicines that can cause electrolyte imbalances.
