What It Measures
This test measures the total amount of carbon dioxide in your blood, which exists mostly as bicarbonate. Bicarbonate is a buffer that helps regulate blood pH. The kidneys and lungs work together to maintain CO2/bicarbonate levels — the lungs exhale CO2 and the kidneys reabsorb or excrete bicarbonate.
CO2 on a basic metabolic panel measures the total carbon dioxide in the blood, primarily in the form of bicarbonate (HCO3⁻). It is a key indicator of acid-base balance and kidney function, reflecting how well the body maintains pH homeostasis. Abnormal levels can signal respiratory disorders, kidney disease, or metabolic disturbances.
Current Value
What High Means
Elevated CO2 (>30 mEq/L) indicates metabolic alkalosis or compensated respiratory acidosis. Common causes include: chronic vomiting or nasogastric suction (loss of stomach acid), diuretic use (especially thiazides and loop diuretics), excessive antacid or bicarbonate intake, Cushing syndrome, hyperaldosteronism, and chronic obstructive pulmonary disease (COPD) with CO2 retention. Severe elevations may indicate significant acid-base disturbance requiring medical attention.
Possible Symptoms
Muscle twitching, hand tremor, numbness or tingling, confusion, prolonged muscle spasms (tetany), nausea, irritability, light-headedness, and in severe cases arrhythmias.
What Low Means
Low CO2 (<23 mEq/L) indicates metabolic acidosis or compensated respiratory alkalosis. Common causes include: diabetic ketoacidosis (DKA), lactic acidosis, chronic kidney disease (impaired bicarbonate reabsorption), severe diarrhea (bicarbonate loss), salicylate or methanol poisoning, renal tubular acidosis, and hyperventilation syndrome. Persistently low levels suggest the body is struggling to buffer acid or is losing bicarbonate.
Possible Symptoms
Rapid or deep breathing (Kussmaul respiration), fatigue, weakness, confusion, nausea, vomiting, headache, bone pain (chronic acidosis), muscle wasting, and in severe cases altered consciousness or shock.
Risk Factors
Chronic kidney disease, COPD, diabetes (risk of DKA), chronic diarrheal illness, diuretic therapy, Cushing syndrome, hyperaldosteronism, chronic vomiting, renal tubular acidosis, heart failure, liver cirrhosis, and severe dehydration.
Actionable Advice
Supplements
- •Sodium bicarbonate
- •Potassium citrate
- •Magnesium citrate
- •Calcium citrate
- •Alkaline mineral supplements
- •Electrolyte blends
Diet & Lifestyle
- •Stay well-hydrated to support kidney function and acid-base balance
- •Eat a balanced diet rich in fruits and vegetables (alkaline-forming foods) to support bicarbonate levels
- •Limit excessive protein and processed food intake which increase acid load
- •Manage chronic conditions like diabetes and kidney disease with your physician
- •Avoid excessive use of antacids or baking soda without medical guidance
- •Practice proper breathing techniques — avoid chronic hyperventilation
- •Limit alcohol consumption which can contribute to metabolic acidosis
- •Monitor medications like diuretics that can affect CO2 levels
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Historical Trend
Resources & Studies
All Readings
| Date | Value | Change |
|---|---|---|
| 2025-08-25 | 25 mmol/L | 0.0 |
| 2025-06-27 | 25 mmol/L | — |