CO2 is carbon dioxide. Measures the amount of carbon dioxide in the liquid part of your blood, called the serum. In the body, 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.
Chloride is a type of electrolyte. It works with other electrolytes such as potassium, sodium, and carbon dioxide (CO2). These substances help keep the proper balance of body fluids and maintain the body's acid-base balance. This is a measure of the amount of chloride in the fluid portion (serum) of the blood.
Potassium is a mineral that the body needs to work normally. It helps nerves and muscles communicate. It also helps move nutrients into cells and waste products out of cells. A diet rich in potassium helps to offset some of sodium's harmful effects on blood pressure.
Sodium is a substance that the body needs to work properly it is vital to normal body processes, including nerve and muscle function