Carbon Dioxide

Total Carbon Dioxide Content (TCO2)

Results

A carbon dioxide test measures the total amount of the three forms of carbon dioxide (bicarbonate, carbonic acid, and dissolved carbon dioxide) in your blood. Results are usually available in 1 to 2 days.

Normal

Carbon dioxide

Adults:	23–29 millimoles per liter (mmol/L)
Children:	20–28 mmol/L
Babies:	13–22 mmol/L

High values

High values may be caused by:

• Diseases that decrease blood pH (respiratory acidosis), such as chronic obstructive pulmonary disease (COPD), emphysema, and pneumonia.
• Diseases that increase blood pH (metabolic alkalosis), such as Cushing's syndrome, Conn's syndrome, and alcoholism.
• Vomiting.

Low values

Low values may be caused by:

• Problems that increase blood pH (respiratory alkalosis), such as pneumonia, cirrhosis, liver failure, or hyperventilation.
• Problems that decrease blood pH (metabolic acidosis), such as uncontrolled diabetes, kidney or heart failure, aspirin overdose, shock, frequent diarrhea, dehydration, long-term (chronic) starvation, and swallowing antifreeze (ethylene glycol) or wood alcohol (methanol).

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Author:	Jeannette Curtis	Last Updated: May 9, 2008
Medical Review:	Kathleen Romito, MD - Family Medicine R. Steven Tharratt, MD, MPVM, FACP, FCCP - Pulmonology, Critical Care, Medical Toxicology
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