Total Carbon Dioxide in Serum or Plasma (as measured by a chemical method)

What Does This Test Measure?

Total CO₂ reflects the combined forms of carbon dioxide in your blood, including bicarbonate (the most abundant) and dissolved CO₂. This measurement indirectly helps evaluate your body’s ability to regulate acid-base balance, which is essential for normal metabolism and respiratory function.

Why Might You Need This Test?

Doctors may order this test if you have symptoms like shortness of breath, fatigue, or signs of acid-base imbalances (e.g., respiratory or metabolic conditions). It can also be part of broader evaluations for chronic lung diseases, kidney function, or metabolic disorders.

How Is the Test Performed?

A blood sample is drawn from a vein, typically in your arm. The sample is sent to a lab where chemical methods detect the total CO₂ content. No special preparation is needed, but fasting may be required depending on your doctor’s instructions.

What Are Common Causes of Abnormal Results?

Elevated CO₂ levels may suggest conditions like respiratory acidosis (e.g., chronic obstructive pulmonary disease) or overproduction of bicarbonate. Low levels could indicate respiratory alkalosis (e.g., hyperventilation) or metabolic acidosis (e.g., kidney issues).