Carbon Monoxide (CO): Results
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Results
A carbon monoxide blood test is used to detect poisoning from breathing carbon monoxide (CO), a colorless, odorless, poisonous gas. The test measures the amount of hemoglobin that has bonded with carbon monoxide. This amount 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.
Results are usually available right away.
Normal
| 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.
| 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.
| Last updated: | March 18, 2008 |
|---|---|
| Author: | Maria G. Essig, MS, ELS |
| Reviewed By: | Caroline S. Rhoads, MD - Internal Medicine, R. Steven Tharratt, MD, MPVM, FACP, FCCP - Pulmonology, Critical Care, Medical Toxicology |
| Editors: | Susan Van Houten, RN, BSN, MBA, Tracy Landauer |
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