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Test Code CO Hgb Carbon Monoxide Hgb

Important Note

Place specimen in outside pocket of a pre-filled biohazard bag of ice, then put into a separate biohazard bag for transport.

Clinical System Name

Carbon Monoxide Hgb


CO (Carbon Monoxide)


Carbon monoxide (CO) poisoning causes anoxia, because CO binds to hemoglobin with an affinity 240 times greater than that of oxygen, thus preventing delivery of oxygen to the tissues. Twenty percent saturation of hemoglobin induces symptoms (headache, fatigue, dizziness, confusion, nausea, vomiting, increased pulse, and respiratory rate). Sixty percent saturation is usually fatal. This concentration is reached when there is 1 part CO per 1,000 parts air.


Carboxyhemoglobin diminishes at a rate of about 15% per hour when the patient is removed from the contaminated environment.


The most common cause of CO toxicity is exposure to automobile exhaust fumes. Significant levels of carboxyhemoglobin can also be observed in heavy smokers. Victims of fires often show elevated levels from inhaling CO generated during combustion. Susceptibility to CO poisoning is increased in anemic persons.


Sample Requirements

Specimen:  Whole Blood (arterial or venous)

Container(s): Heparinized Syringe, Capillary Blood Gas Tube

Preferred Vol: 0.5 mL arterial or venous blood in a Heparinized Syringe

Minimum Vol: 2 Heparinized Capillary Blood Gas Tubes. (EPOC capillary tubes are not acceptable).


Note: Use only Arterial Blood Sample syringe with dry Lithium Heparin for gases and electrolytes or heparinized capillary blood gas tubes. Send to the lab immediately. Avoid air bubbles. Expel air from syringe and cap it immediately after obtaining the sample. Capillary blood gas tubes must be filled completely and mixed thoroughly to dissolve and disperse the heparin. EPOC capillary tubes are not acceptable. Ideally, whole blood specimens should be analyzed within 15 minutes of blood draw. Place specimen in outside pocket of a pre-filled biohazard bag of ice, then put into a separate biohazard bag for transport.


Processing Instructions

Reject due to: Inadequately filled specimens, air bubbles, visible clots, age of specimen


Spin: N

Aliquot: N


Off-site collection: Sample must be collected at Children's.  Please contact Laboratory (206) 987-2617 for additional information.




Specimen Type Temperature Time
Heparinized Syringe, Heparinized Capillary Blood Gas Tube RT ≤ 15 min.
Heparinized Syringe, Heparinized Capillary Blood Gas Tube 0-4o C 30 min
  -20o C or -70oC No



STAT Performed TAT
Y 24/7 15 M


Performing Laboratory

Seattle Children's Laboratory    


Department:  Chemistry - Core

Phone Number: 206-987-2617

Reference Range

Normal environmental exposure: 0.5 - 1.5%

Smokers: ≤ 9%

Toxic concentration: 20%




Method: Oximetry by SIEMENS RAPIDPOINT 405

Analytical Volume:



0-2 Y  0.2 mL Heparinized Capillary Blood Gas Tube
> 2 Y 0.5 mL Heparinized Syringe


CPT Codes