Carbon Dioxide · low result
What does a low Carbon Dioxide mean?
Short answer
Low serum CO2 (bicarbonate) means acid is accumulating or bicarbonate is being lost: uncontrolled diabetes, kidney disease, diarrhea, some medications (acetazolamide, topiramate, metformin in rare cases), heavy exercise or alcohol, and toxic ingestions. Hyperventilation from anxiety also lowers it. The anion gap and glucose decide how urgent it is.
Medically reviewed by Youmna DiStefano, MD · Last reviewed September 2026
When does this result need same-day care?
- CO2 below ~15 mmol/L, or a low value with vomiting, deep rapid breathing or confusion — emergency care
What is the normal range for Carbon Dioxide?
- age 18+: 22.0 – 29.0 mmol/L
Full reference table, citations and testing options: Carbon Dioxide biomarker page.
What are the common causes of low Carbon Dioxide?
- Diabetic ketoacidosis, starvation or alcoholic ketosis
- Chronic kidney disease, renal tubular acidosis
- Severe diarrhea
- Medications: acetazolamide, topiramate, high-dose aspirin
- Lactic acidosis from sepsis or severe illness; toxic alcohols
- Chronic hyperventilation, under-filled tube (mild false low)
What symptoms go with low Carbon Dioxide?
- Rapid breathing, nausea, fatigue, confusion when significant
- Often none when mild
What do clinicians usually check next?
- Glucose, kidney function, potassium, chloride (anion gap); lactate if unwell
- Medication review
- Urine studies for renal tubular acidosis when persistent
Follow-up tests available at TestWell: Glucose ($14.99).
How do you recheck Carbon Dioxide?
Prices are cash-pay; every order adds one $6 lab processing fee. Physician authorization is included; no insurance or referral needed.
| Test or panel | Type | Price | Fasting | Results |
|---|---|---|---|---|
| Basic Metabolic Panel | Test · 8 biomarkers | $20.99 | Yes | 1–3 business days |
Common questions
Can anxiety lower my CO2 on a blood test?
Yes — sustained fast breathing blows off CO2 and the bicarbonate falls a little to compensate. That pattern is mild and harmless; large drops need a metabolic explanation.
Sources
Educational content, not a diagnosis. Lab results are one input; a clinician interprets them with your history and exam.