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Carbon Dioxide Concentration in Cerebrospinal Fluid (CSF)

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

This test measures the amount of carbon dioxide dissolved in your cerebrospinal fluid (the fluid surrounding your brain and spinal cord). It helps assess how well your body is balancing acidity and alkalinity in this area.

Quick summary

["A key check for potential imbalances in brain chemistry that could affect neurological health."]

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

Key facts at a glance

LOINC
13540-0
Short code
CO2 CSF-sCnc
Synonyms
CO2 CSF-sCnc
Category
chemistry
Sample
csf
Container
Sterile tube
Units
N/A
Ref low
22
Ref high
28
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82374
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your doctor may order this test if you have symptoms like severe headaches, nausea, vomiting, confusion, or neurological issues that could suggest conditions like meningitis, brain swelling, or metabolic disorders. It’s also used in certain diagnostic evaluations for neurological or systemic diseases.

What to Expect Before the Test

No special preparation is needed. The test involves a small needle inserted into your lumbar spine to collect a sample of CSF. You may feel mild pressure or discomfort, but it usually doesn’t require sedation.

What the Results Mean

Results are compared to standard ranges for CSF carbon dioxide, though exact values can vary by lab. Abnormally low levels may indicate conditions like meningitis or brain swelling, while high levels could suggest metabolic issues or other neurological concerns.

Common Conditions Monitored

This test helps diagnose or monitor conditions such as hydrocephalus, brain tumors, infections (like encephalitis), or metabolic disorders affecting acid-base balance.

Reference range

Adult: 22-28 mmol/LN/A

Specimen: csf

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.

◆Associated findings1

Short name

CSF CO₂ Level

Frequently asked questions

How often will I need this test?
The frequency depends on your symptoms, diagnosis, or treatment plan. Your doctor will determine if repeat testing is needed based on your condition and response to treatment.
What are the risks or side effects of this test?
The most common risk is a mild headache or soreness at the injection site. Rarely, there may be temporary nerve pain or a small risk of infection. Most people experience minimal discomfort.
Can I drink or eat before this test?
You can eat and drink normally before the test unless your doctor specifies otherwise. Avoid alcohol or caffeine in excess, as they may affect your blood pressure or neurological symptoms.
  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