Skip to content

Total Serum Carbon Dioxide (as Bicarbonate)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of carbon dioxide in your blood, primarily in the form of bicarbonate, which helps regulate your body’s acid-base balance.

Quick summary

["Your blood’s bicarbonate levels help maintain healthy pH and support normal bodily functions."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
57921-9
Short code
CO2 BldCoA Calc-sCnc
Synonyms
CO2 BldCoA Calc-sCnc
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
22
Ref high
28
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
calculated
CPT
82374
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why This Test Is Done

Doctors may order this test to check for conditions affecting acid-base balance, such as metabolic acidosis or alkalosis, or to monitor kidney function, respiratory issues, or other health problems that could influence blood chemistry.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm to draw blood. If you’re concerned about discomfort, let your healthcare provider know.

What the Results Mean

Results help determine if your bicarbonate levels are too high or too low, which can indicate underlying health concerns. Your doctor will interpret the results in the context of your overall health.

Common Conditions Monitored

This test is often used to diagnose or monitor conditions like kidney disease, diabetes, heart failure, or respiratory disorders that affect how your body processes acids and bases.

Reference range

Adult: 22-28 mmol/LN/A

Specimen: whole-blood

No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Bicarbonate Levels and Health

Short name

Total CO₂ (Serum)

Frequently asked questions

What causes blood bicarbonate levels to change?
Changes in bicarbonate levels can be caused by conditions like kidney disease (which affects bicarbonate production), respiratory disorders (like chronic obstructive pulmonary disease), metabolic disorders (like diabetes), or excessive vomiting or diarrhea that alter acid-base balance.
How often should I get this test?
Your doctor will determine how often you need this test based on your health status, symptoms, and treatment plan. Regular monitoring may be needed if you have chronic conditions like kidney disease or heart failure.
Can diet affect bicarbonate levels?
Yes, certain foods and drinks—like those high in sodium, potassium, or protein—can influence bicarbonate levels. Your doctor may recommend dietary adjustments if needed, but this test alone won’t show dietary impacts directly.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy