Bicarbonate (reported as CO₂ or total CO₂) is the body's main buffer that keeps the blood from becoming too acidic.
- Normal range (adults)
- 23–29 mmol/L
- Sample
- Blood
- Fasting
- Not usually needed
- Also called
- CO2, Bicarbonate, HCO3, Total CO2, Serum CO2, Bicarb
Bicarbonate normal range
| Group | mmol/LSame unit in all countries |
|---|---|
| Adults | 23–29 |
Ranges vary slightly between laboratories. The range printed on your own report is the one to go by.
Why is the Bicarbonate test done?
It is part of the electrolyte panel and helps detect acid-base problems.
What does a high Bicarbonate level mean?
High bicarbonate (metabolic alkalosis) usually follows vomiting or diuretic use.
Common causes
- Prolonged vomiting
- Diuretics
- Excessive antacid use
- Low potassium
Diet and lifestyle tips
- Rehydrate after vomiting
- Avoid excessive antacids or baking soda
What does a low Bicarbonate level mean?
Low bicarbonate (metabolic acidosis) means acid is building up in the blood.
Common causes
- Kidney disease
- Diabetic ketoacidosis
- Severe diarrhoea
- Severe infection
- Some medicines, such as metformin in kidney failure (rare)
Diet and lifestyle tips
- Treat the underlying cause; in kidney disease your doctor may prescribe bicarbonate
- More fruit and vegetables and less meat can help in chronic kidney disease
When should you see a doctor?
A low bicarbonate with vomiting, rapid breathing or high blood sugar needs urgent care.
Last updated
This page is for general education and is not a diagnosis. Normal ranges differ between laboratories, so always compare your result with the reference range printed on your own report, and discuss abnormal results with your doctor.