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HelpTest Code LAB56 Carbon Monoxide (Carboxyhemoglobin/COHb), Blood
Useful For
Verifying carbon monoxide toxicity in cases of suspected exposure
Methodology
Specific Electrodes
Performing Laboratory
Bozeman Health Laboratory Services
Specimen Requirements
Specimen Type: Whole blood
Container/Tube: Dark green top without gel (sodium heparin)
Specimen Volume: 2 mL
Specimen Minimum Volume: 1 mL
Collection Instructions: Avoid exposure of specimen to atmosphere by keeping specimen capped in original container. Do not centrifuge. Place a piece of tape over the cap to alert specimen processing not to spin specimen.
Specimen Transport Temperature
Ambient
Specimen Stability
| Specimen Type | Temperature | Time |
|---|---|---|
| Whole blood (uncapped) | Ambient | 30 minutes |
| Whole blood (capped) | Ambient | 2 days |
Reference Values
| % CO Hgb | 0.5%-2.0% THgb | ||
| Smokers | 1-2 packs/day | 4.0%-5.0% THgb | |
| >2 packs/day | 8.0%-9.0% THgb | ||
| Toxic | >20.0% THgb | ||
| Lethal | >50.0% THgb |
Critical value (automatic call-back): >15.0%
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.
Day(s) Test Set Up
Monday through Sunday
Test Classification and CPT Coding
82375