A carbon monoxide blood test is used to detect carbon monoxide poisoning. Poisoning can happen if you breathe air that contains too much carbon monoxide (CO). This gas has no colour, odour, or taste, so you can't tell when you are breathing it. The test measures the amount of hemoglobin in your blood that has bonded with carbon monoxide.
Carbon monoxide can come from any source that burns fuel. Common sources are cars, fireplaces, powerboats, woodstoves, kerosene space heaters, charcoal grills, and gas appliances such as water heaters and ovens. These things usually cause no problems. But if they are not used or installed properly, carbon monoxide may build up in an enclosed space.
When you inhale carbon monoxide, it replaces the oxygen that is normally carried by the hemoglobin in your red blood cells. As a result, your brain and other tissues get less oxygen. This can cause serious symptoms or death.
Why It Is Done
This test may be done if you have been exposed to carbon monoxide or if you have unexplained symptoms, such as:
Headache, dizziness, or vision problems.
Nausea or vomiting.
Confusion or trouble thinking.
How To Prepare
Do not smoke before you have this test. Tobacco smoke contains carbon monoxide.
How It Is Done
A health professional uses a needle to take a blood sample, usually from the arm.
How It Feels
When a blood sample is taken, you may feel nothing at all from the needle. Or you might feel a quick sting or pinch.
There is very little chance of having a problem from this test. When a blood sample is taken, a small bruise may form at the site.
The results are reported as a percentage. They show the amount of carbon monoxide bound to hemoglobin divided by the total amount of hemoglobin (multiplied by 100). This is called the carboxyhemoglobin level.
Results are usually available right away.
Each lab has a different range for what's normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn't in the normal range may still be normal for you.
Author: Healthwise Staff Medical Review: Anne C. Poinier MD - Internal Medicine Kathleen Romito MD - Family Medicine E. Gregory Thompson MD - Internal Medicine Adam Husney MD - Family Medicine R. Steven Tharratt MD, MPVM, FACP, FCCP - Pulmonology, Critical Care Medicine, Medical Toxicology
Medical Review:Anne C. Poinier MD - Internal Medicine & Kathleen Romito MD - Family Medicine & E. Gregory Thompson MD - Internal Medicine & Adam Husney MD - Family Medicine & R. Steven Tharratt MD, MPVM, FACP, FCCP - Pulmonology, Critical Care Medicine, Medical Toxicology
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