Results
A carbon monoxide blood test is used to
detect
from breathing carbon monoxide (CO), a
colorless, odorless, poisonous gas. The test measures the amount of hemoglobin
that has bonded with carbon monoxide. This is also called the
carboxyhemoglobin level.
Carbon monoxide results are reported as
a percentage: The amount of carbon monoxide bound to hemoglobin is divided by
the total amount of hemoglobin (and then multiplied by 100). The higher the
percentage, the greater the risk of having symptoms of carbon monoxide
poisoning. With values below 10%, a person may not have any symptoms of
poisoning.
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what’s normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
Results are usually available right away.
Normal
Carbon monoxide| Nonsmokers: | Less than 3% of total hemoglobin |
|---|
| Smokers: | 2%–10% of total hemoglobin |
|---|
High values
High blood
carbon monoxide values are caused by carbon monoxide poisoning. Symptoms of
carbon monoxide poisoning become more severe as the carbon monoxide levels
increase.
Symptoms related to high carbon monoxide values| Percent of total hemoglobin | Symptoms |
|---|
20%–30% | Headache, nausea, vomiting, and trouble
making decisions |
30%–40% | Dizziness, muscle weakness, vision
problems, confusion, and increased heart rate and breathing rate |
50%–60% | Loss of consciousness |
Over 60% | Seizures, coma, death |
Women and children may have more severe symptoms of carbon
monoxide poisoning at lower carbon monoxide levels than men because women and
children usually have fewer red blood cells.