carboxyhemoglobin in blood

Reference interval

• non-smokers: 0.5-1.5% of hemoglobin
• smokers (1-2 packs/day): 4-5% of hemoglobin
• heavy smokers (> 2 packs/day): 8-9% of hemoglobin
  • up to 15%
  • a carboxyhemoglobin in blood > 15% suggests carbon monoxide poisoning
• toxic: > 20% of hemoglobin
• lethal: > 50% of hemoglobin

Clinical significance

• also see carbon monoxide poisoning
• levels of carbon monoxide of < 10% may increase disturbances of cognitive function or aggravate pre-existing heart disease
• levels of 15-25% may cause dizziness & nausea
• 1/2 life is reduced from 5 hours to 80 minutes with oxygen & to 24 minutes with hyperbaric O2 (3 atmospheres)

Increases

• smoking
• exposure to gases:
  • defective furnaces
  • automobile exhaust
  • coal gas
  • most combustibles
  • methylene chloride
• hemolytic disease
• blood in intestine

Methods

• colorimetric
• GLC

Specimen

• whole blood (heparin)
• stable for > 4 months in filled, well-capped tube
• do NOT use oxalate
• collect specimen BEFORE treatment with oxygen

More general terms

• clinical hematology test

More specific terms

• carboxyhemoglobin in cord blood

Additional terms

• carbon monoxide poisoning
• carboxyhemoglobin