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Carbon Monoxide, Whole Blood

CPT: 82375
Updated on 05/20/2019
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  • Carboxyhemoglobin, Blood

Test Includes

Carboxyhemoglobin, blood

Carboxyhemoglobin, blood

Expected Turnaround Time

2 - 5 days

Specimen Requirements


Whole blood


7 mL

Minimum Volume

0.6 mL


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


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

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.

Causes for Rejection

Clotted specimen

Test Details


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


Carbon monoxide levels are of limited value in testing for smoking, since it is cleared rapidly. The half-life of carboxyhemoglobin in individuals with normal cardiopulmonary function is one to two hours. Urinary cotinine, if available, is preferable as a test for tobacco use. Arterial blood gases may be of limited value in treatment decisions for carbon monoxide poisoning.2



Reference Interval

Environmental exposure: Nonsmoker: <2.0%, smoker: <9.0%

Occupational exposure: BEI®: 3.5%1

Additional 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.

A danger of missed diagnosis of CO intoxication is continued exposure of the patient and others to a toxic environment.3 The cherry red color of CO poisoning is not consistently seen.4 CO intoxication may contribute to the risk of myocardial infarction.4,5

A strong correlation is present between carboxyhemoglobin levels and psychometric testing abnormalities.2 Psychometric testing measures actual neurologic disability and may therefore better define carboxyhemoglobin poisoning severity than blood CO level.


1. BEI® (Biological Exposure Indices) based on 2010 Recommendations of the American Conference of Governmental Industrial Hygienists (ACGIH).
2. Myers RA, Britten JS. Are arterial blood gases of value in treatment decisions for carbon monoxide poisoning? Crit Care Med. 1989 Feb; 17(2):139-142. 2644066
3. Carbon monoxide poisoning in the home. BMJ. 1990 Nov 17; 301(6761):1161. 2252933
4. Grace TW, Platt FW. Subacute carbon monoxide poisoning. Another great imitator. JAMA. 1981 Oct 9; 246(15):1698-1700. 7277647
5. Kaufman DW, Helmrich SP, Rosenberg L, Miettinen OS, Shapiro S. Nicotine and carbon monoxide content of cigarette smoke and the risk of myocardial infarction in young men. N Engl J Med. 1983 Feb 24; 308(8):409-413. 6823250


Dolan MC, Haltom TL, Barrows GH, Short CS, Ferriell KM. Carboxyhemoglobin levels in patients with flu-like symptoms. Ann Emerg Med. 1987 Jul; 16(7):782-786. 3592333
Fechner GG, Gee DJ. Study on the effects of heat on blood and on the postmortem estimation of carboxyhemoglobin and methaemoglobin. Forensic Sci Int. 1989 Jan; 40(1):63-67. 2925132
Heckerling PS, Leikin JB, Maturen A, Terzian CG, Segarra DP. Screening hospital admissions from the emergency department for occult carbon monoxide poisoning. Am J Emerg Med. 1990 Jul; 8(4):301-304. 2094235
Krantz T, Thisted B, Strøm J, Sørensen MB. Acute carbon monoxide poisoning. Acta Anaesthesiol Scand. 1988 May; 32(4):278-282. 3394478
Thom SR, Keim LW. Carbon monoxide poisoning: A review epidemiology, pathophysiology, clinical findings, and treatment options including hyperbaric oxygen therapy. J Toxicol Clin Toxicol. 1989; 27(3):141-156. 2681810
Variend S, Forrest AR. Carbon monoxide concentrations in infant deaths. Arch Dis Child. 1987 Apr; 62(4):417-418. 3592735
Zijlstra WG, Buursma A, Meeuwsen-van-der-Roest WP. Absorption spectra of human fetal and adult oxyhemoglobin, deoxyhemoglobin, carboxyhemoglobin, and methemoglobin. Clin Chem. 1991 Sep; 37(9):1633-1638. 1716537


Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
007187 Carbon Monoxide, Blood 20563-3 007189 Carbon Monoxide, Blood % 20563-3

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