Test Catalog

Test Id : COHBB

Carbon Monoxide, Blood

Useful For
Suggests clinical disorders or settings where the test may be helpful

Verifying carbon monoxide toxicity in cases of suspected exposure

Method Name
A short description of the method used to perform the test

Carboxyhemoglobin Co-oximetry

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Carbon Monoxide, B

Lists additional common names for a test, as an aid in searching


CO (Carbon Monoxide)

Carbon Monoxide (Carboxyhemoglobin)

Specimen Type
Describes the specimen type validated for testing

Whole Blood EDTA

Ordering Guidance

This test is not available for autopsy or cadaver specimens.

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Container/Tube: Lavender top (EDTA)

Specimen Volume: 1 mL

Collection Instructions: Avoid exposure of specimen to atmosphere.


If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

0.1 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Whole Blood EDTA Ambient (preferred) 14 days
Frozen 14 days
Refrigerated 14 days

Useful For
Suggests clinical disorders or settings where the test may be helpful

Verifying carbon monoxide toxicity in cases of suspected exposure

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Carbon monoxide (CO) is a colorless, odorless, tasteless gas that is a product of incomplete combustion of carbonaceous material. CO poisoning causes hypoxia because CO binds to hemoglobin with an affinity 250 times greater than that of oxygen, thus preventing delivery of oxygen to the tissues, but concentrations greater than 20% are associated with symptoms of toxicity (eg, headache, fatigue, dizziness, confusion, nausea, vomiting, increased pulse and respiratory rate). CO levels greater than 50% are potentially fatal. Common exogenous sources of carbon monoxide include cigarette smoke, gasoline engines, and improperly ventilated home heating units. Small amounts of carbon monoxide are produced endogenously in the metabolic conversion of heme to biliverdin. This endogenous production of carbon monoxide is accelerated in hemolytic anemias.

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Normal Concentration

Non-Smokers: 0-2%

Smokers: < or =9%

Toxic concentration: > or =20%

Provides information to assist in interpretation of the test results

The toxic effects of carbon monoxide can be seen in levels above 20% carboxyhemoglobin. It must be emphasized that the carboxyhemoglobin concentration, although helpful in diagnosis, does not always correlate with the clinical findings or prognosis. Factors other than carboxyhemoglobin concentration that contribute to toxicity include length of exposure, metabolic activity, and underlying disease, especially cardiac or cerebrovascular disease. Moreover, low carboxyhemoglobin concentrations relative to the severity of poisoning may be observed if the patient was removed from the carbon monoxide-contaminated environment a significant amount of time before blood sampling.


An insidious effect of carbon monoxide poisoning is the delayed development of neuropsychiatric sequelae, which may include personality changes, motor disturbances, and memory impairment. These manifestations do not correlate with the length of exposure or with the maximum blood carboxyhemoglobin concentration.

Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

No significant cautionary statements

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Langman LJ, Bechtel LK, Meier BM, Holstege C: In Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Sixth edition. Chapter 41: Clinical toxicology. Edited by N Rifai, AR Horvath, CT Wittwer. Elsevier; 2018. pp 832-887

2. Disposition of Toxic Drugs and Chemicals in Man. 10th edition. Edited by RC Baselt. Biomedical Publications, 2014

Method Description
Describes how the test is performed and provides a method-specific reference

The ABL80 OSM CO-OX analyzer is a portable, automated analyzer that measures oximetry in whole blood. Total hemoglobin (tHb), oxygen saturation (sO2), carboxyhemoglobin (COHb), and methemoglobin (MetHb) are measured by spectrophotometry. Light passes through a cuvette containing hemolyzed blood sample. The specific wavelengths absorbed and their intensity generates an absorption spectrum used to calculate oximetry parameters.(Instruction manual: ABL80 FLEX CO-OX analyzer-OSM version, Radiometer Medical ApS, 2016)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Friday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

Same day/1 to 3 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test


Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.


LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
COHBB Carbon Monoxide, B 20563-3
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
8649 Carbon Monoxide, B 20563-3

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports

Test Update Resources

Change Type Effective Date
Test Status - Test Resumed 2023-01-09
Test Status - Test Delay 2023-01-06