Carbon Monoxide

Test ID: 


CPT code:



Carboxyhemoglobin, Blood

Clinical Use:

Determine the extent of carbon monoxide poisoning, toxicity; check on the effect of smoking on the patient; work up headache, irritability, nausea, vomiting, vertigo, dyspnea, collapse, coma, convulsions; work up persons exposed to fires and smoke inhalation.

Additional Test Information:

Carboxyhemoglobin is useful in judging the extent of carbon monoxide toxicity and in considering the effect of smoking on the patient. A direct correlation has been claimed between CO level and symptoms of atherosclerotic diseases, intermittent claudication, angina, and myocardial infarction. Exposure may occur not only from smoking but also from garage exposure, and from various motors. This test may be included when blood gases are ordered, when there is sufficient sample, and when such instrumentation is available.

Specimen Type:

Whole blood

Requested Volume: 

7 mL

Minimum Volume: 

0.6 mL

Container Type: 

Lavender-top (EDTA) tube or green-top (heparin) tube; submit original full, unopened tube

Patient Preparation: 

A morning specimen is not as good as one that is drawn in the late afternoon or evening, especially if the patient is an outpatient who may have occupational exposure (ie, policemen, firemen on day shifts, mechanics). CO tends to be cleared from the blood in hours. Treatment for carbon monoxide poisoning involves removal of the individual from the contaminated area and the administration of oxygen. The half-life of carboxyhemoglobin is five to six hours when the patient breathes room air; it is reduced to 1 to 11/2 hours when the patient breathes 100% oxygen. In severe cases, hyperbaric oxygen treatment at two to three atmospheres is recommended, if available. In the latter instance, the carboxyhemoglobin half-life is reduced to approximately 25 minutes. Hyperbaric oxygen therapy may reduce the incidence of neurological manifestations after exposure. Hyperbaric oxygen therapy has been recommended when the carboxyhemoglobin concentration exceeds 25%. Some have cautioned against basing decisions to institute hyperbaric oxygenation solely on the carboxyhemoglobin concentration owing to the inconsistent correlation between such a measurement and clinical severity.


Sampling time is end of shift for industrial exposure monitoring. Analytes with timing “end of shift” (meaning the last two hours of exposure) are eliminated rapidly with a half-life less than five hours. Such compounds do not accumulate in the body and, therefore, their timing is critical only in relation to the exposure period.

Storage Instructions:

Refrigerate immediately after collection. Do not remove cap.

Stability Requirements




28 days


Rejection Criteria

Clotted specimen

Return Back to Test Directory

MCI Diagnostic

Providing top patient care with fast results. 

7018 South Utica Avenue

Tulsa, Oklahoma 74136

Hours of Operation

Mon – Sat: 7AM-11PM

Sun: 7AM-3PM

Government Contract

Mon – Sat: 7AM-11PM

Sun: 7AM-3PM


Mon – Sat: 7AM-11PM

Sun: 7AM-3PM

Thank you for uploading your files. Your upload has been submitted successfully.