The normal blood carbon dioxide levels is 23 to 29 milliequivalents per liter (mEq/L). The level of carbon dioxide in the liquid component of the blood is measured by a test called CO2 blood test. The mEq/L value represents 1,000th parts of a substance that is dissolved in 1 liter of plasma or solution.
Also known as bicarbonate test, the CO2 blood test is more often conducted as part of a basic metabolic or electrolyte panel. Any deviation in an individual's CO2 levels may mean that he or she is either retaining or losing fluid. Technically, the carbon dioxide in the body is in bicarbonate form, so a CO2 blood test can also be referred to as a bicarbonate test.
The CO2 blood test is conducted by drawing blood from a vein located at the back of the hand or on the inside part of the elbow. Since certain drugs may interfere with the test, a medical professional may advise an individual to stop taking the medications for a certain period until the test is done.
The function of the kidneys and the lungs affect the CO2 blood levels, with kidneys playing a role in maintaining the bicarbonate levels of the blood. When the CO2 blood levels are higher than the normal values, it may indicate Cushing's syndrome, breathing problems or hyperaldosteronism. Lower than normal values may indicate conditions such as kidney disease, Addison's disease or ketoacidosis.