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Also known as: Total CO2; TCO2; Carbon Dioxide Content; CO2 Content; Bicarb; HCO3-
Formal name: Bicarbonate

Total CO2 or bicarbonate is different than the partial pressure of CO2 (PCO2). Learn about PCO2

The Test Sample

What is being tested?

The total CO2 test measures the total amount of carbon dioxide in the blood, which occurs mostly in the form of bicarbonate (HCO3-). Bicarbonate is a negatively charged ion that is excreted and reabsorbed by the kidneys. It is used by the body to help maintain the body's acid-base balance (pH) and secondarily to work with sodium, potassium, and chloride to maintain electrical neutrality at the cellular level.

Measuring bicarbonate (or total CO2) as part of an electrolyte or metabolic panel may help diagnose an electrolyte imbalance or acidosis or alkalosis as the result of a disease process or condition.

How is the sample collected for testing?

A blood sample is drawn by needle from a vein in the arm.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.