Kidney system

Carbon Dioxide (CO₂)

CO₂

The blood's buffering capacity — a marker of acid-base balance.

What is it

Carbon Dioxide (CO₂) — in plain English.

Total carbon dioxide reflects bicarbonate levels in blood and indicates buffering capacity for acid-base balance.

Why it's measured

What CO₂ can reveal.

CO₂ has been used in evaluating acid-base status and respiratory function in clinical research.

Reference range

Where most laboratories draw the standard line.

Standard laboratory reference

23 – 29 mEq/L

Reference ranges vary by laboratory. Your individual reference range will appear on your test report and should be interpreted by your physician in the context of your overall health profile.

What results may indicate

Higher vs. lower CO₂ — at a high level.

Elevated

Has been associated with respiratory and metabolic alkalosis in research literature.

Lower

Has been associated with metabolic acidosis in research literature.

These associations are general. They are not a personal diagnosis or prediction. Discuss your individual results with your physician in the context of your full health profile.

When it's measured

When CO₂ is typically run.

Part of standard electrolyte panels.

Related markers

Often measured alongside CO₂.

Measured in

CO₂ is one of 160 biomarkers in the Apex Panel.

A complete look at your heart, hormones, metabolism, inflammation, and longevity systems — drawn at Quest or LabCorp, reviewed by a U.S.-licensed physician.

Explore the Apex Panel
160 biomarkers13 body systemsPhysician-reviewed
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This information is for general educational purposes only and is not medical advice. Lab results alone are not intended to diagnose, treat, or cure any condition and do not replace the advice of a healthcare provider. OPTML does not offer medical advice, a diagnosis, medical treatment, or any form of medical opinion.