Carbon dioxide
ChemistryAlso known as: CO2Also known as: BicarbonateAlso known as: Carbonic acidmmol/L
Measures blood carbon dioxide levels to assess respiratory and acid-base function.
Normal Range
23 – 29 mmol/L
mmol/L
Abnormal Levels
< 22 mmol/L
> 36 mmol/L
Specimen Type
Blood
Why This Biomarker Matters
Abnormal blood CO2 indicates respiratory disease, kidney dysfunction, or metabolic imbalance affecting oxygen delivery. This test guides diagnosis of breathing and metabolic disorders.
Understanding Your Results
Normal Range
23 – 29 mmol/L
Optimal Ranges
Clinician-defined 4-point reference thresholds (mmol/L)
Default Range
22
26
32
36
Low
22 mmol/L
Borderline Low
26 mmol/L
Optimal
32 mmol/L
Borderline High
36 mmol/L
Overview
Carbon dioxide (CO2) in blood, measured as bicarbonate, is crucial for acid-base balance and respiration. This test assesses how well your lungs remove CO2 and how well your kidneys regulate acid balance. Elevated CO2 suggests respiratory problems or metabolic alkalosis, while low CO2 may indicate hyperventilation or metabolic acidosis. Results help diagnose breathing disorders, kidney disease, and serious metabolic imbalances affecting multiple organ systems.
Research & Evidence
100 publications
Sort:
Molecular Changes Induced by Carbon Dioxide Laser in Hailey-Hailey Disease: A Potential Mechanism Underlying Treatment Efficacy.
Int J Dermatol · 2026
PMID: 41498265Other
Glyphosate use in agricultural production: it's contribution to global carbon dioxide emissions.
GM Crops Food · 2026
PMID: 41411675Other
Systematic review and meta-analysis of acute hypoxia and cognition: Domain-specific effects and the role of barometric pressure and carbon dioxide.
Neurosci Biobehav Rev · 2026
PMID: 41672258
Exercise modality and cerebral hemodynamics in older adults: A systematic review and network meta-analysis.
Physiol Behav · 2026
PMID: 41692180
Comparing CO2 Laser Wedge Resection to Radial Incision With Dilation in the Endoscopic Treatment of Benign Tracheal Stenosis: A Systematic Review.
J Bronchology Interv Pulmonol · 2026
PMID: 41718210
Simultaneous detection of methane and carbon dioxide in human exhalation based on photoacoustic spectroscopy.
Photoacoustics · 2026
PMID: 41809365
Research data from MEDLINE/PubMed · 100 articles
Technical Information (LOINC Codes)
Standardized laboratory codes for this biomarker
2028-9PrimaryCarbon dioxide, total [Moles/volume] in Serum or Plasma
mmol/L
39465-0Carbon dioxide, total [Moles/volume] in Venous cord blood
mmol/L
14040-0Carbon dioxide, total [Moles/volume] in Stool
mmol/L
32306-3Carbon dioxide [Partial pressure] in Urine
mm[Hg]
14640-7Carbon dioxide, total [Moles/volume] in Dialysis fluid
mmol/L
13538-4Carbon dioxide, total [Moles/volume] in Urine
mmol/L
14003-8Carbon dioxide [Partial pressure] in Cord blood
mm[Hg]
57920-1Carbon dioxide, total [Moles/volume] in Mixed venous blood by calculation
mmol/L
16551-4Carbon dioxide, total [Moles/volume] in Capillary blood
mmol/L
57923-5Carbon dioxide, total [Moles/volume] in Venous cord blood by calculation
mmol/L
57921-9Carbon dioxide, total [Moles/volume] in Arterial cord blood by calculation
mmol/L
34520-7Carbon dioxide, total [Moles/volume] in Cord blood
mmol/L
51781-3Carbon dioxide, total [Moles/volume] in Capillary blood by calculation
mmol/L
34728-6Carbon dioxide, total [Moles/volume] in Blood by calculation
mmol/L
11211-0Carbon dioxide, total [Moles/volume] in Body fluid
mmol/L
48391-7Carbon dioxide, total [Moles/volume] in Venous blood by calculation
mmol/L
19223-7Carbon dioxide, total [Moles/volume] in Mixed venous blood
mmol/L
38253-1Carbon dioxide, total [Moles/volume] in Specimen
mmol/L
28645-0Carbon dioxide [Partial pressure] in Venous cord blood
mm[Hg]
28644-3Carbon dioxide [Partial pressure] in Arterial cord blood
mm[Hg]
39466-8Carbon dioxide, total [Moles/volume] in Arterial cord blood
mmol/L
2027-1Carbon dioxide, total [Moles/volume] in Venous blood
mmol/L
19212-0Carbon dioxide [Partial pressure] in Mixed venous blood
mm[Hg]
2020-6Carbon dioxide [Partial pressure] in Capillary blood
mm[Hg]
41647-9Carbon dioxide, total [Moles/volume] in Arterial blood by calculation
mmol/L
2026-3Carbon dioxide, total [Moles/volume] in Arterial blood
mmol/L
20565-8Carbon dioxide, total [Moles/volume] in Blood
mmol/L
2021-4Carbon dioxide [Partial pressure] in Venous blood
mm[Hg]
2019-8Carbon dioxide [Partial pressure] in Arterial blood
mm[Hg]
11557-6Carbon dioxide [Partial pressure] in Blood
mm[Hg]
53458-6Carbon dioxide [Partial pressure] in Nonbiological fluid
mm[Hg]
13540-0Carbon dioxide, total [Moles/volume] in Cerebral spinal fluid
mmol/L
57922-7Carbon dioxide, total [Moles/volume] in Serum or Plasma by calculation
mmol/L
59165-1Carbon dioxide [Partial pressure] in Dialysis fluid
mm[Hg]
77143-6Carbon dioxide, total [Moles/volume] in Serum, Plasma or Blood
mmol/L
97538-3Carbon dioxide [Partial pressure] in Central venous blood
mm[Hg]
97545-8Carbon dioxide, total [Moles/volume] in Central venous blood
mmol/L
2023-0Carbon dioxide [Partial pressure] in Body fluid
mm[Hg]
35685-7Carbon dioxide [Moles/volume] in Urine collected for unspecified duration
nmol/L
2022-2Carbon dioxide [Partial pressure] in Cerebral spinal fluid
mm[Hg]
39464-3Carbon dioxide, total [Moles/volume] in Peritoneal dialysis fluid
mmol/L
2018-0Carbon dioxide [Partial pressure] in Amniotic fluid
mm[Hg]
53089-9Carbon dioxide, total [Moles/volume] in Nonbiological fluid by calculation
mmol/L
53090-7Carbon dioxide, total [Moles/volume] in Nonbiological fluid
mmol/L
Available Lab Tests
Order tests that measure this biomarker
Adrenal Complete
$340.56
Advanced Cardiovascular Health Basic
$132.55
Advanced Cardiovascular Health Comprehensive
$526.57
Advanced Liver Health Basic
$293.92
Advanced Liver Health Comprehensive
$1044.34
Cancer Tumor Markers Men Basic
$71.57
Carbon Dioxide
$8.86
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Comprehensive Metabolic Panel (CMP)
$15.79
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