Carboxyhemoglobin

Carboxyhemoglobin (CO hemoglobin, HbCO) is formed as a result of hemoglobin binding with carbon monoxide – an odorless, colorless, and non-irritating gas produced during incomplete combustion of natural gas. Poisonings most often occur via inhalation, especially during the autumn and winter months. Carbon monoxide has 200–250 times greater affinity for hemoglobin than oxygen. When hemoglobin binds with CO, its molecular structure changes, and it is no longer able to transport oxygen to tissues and organs, leading to reduced oxygenation.

Symptoms of carboxyhemoglobin poisoning include headache, confusion, weakness, and in severe cases, coma and respiratory depression. Carbon monoxide poisoning may also lead to muscle damage. Measuring HbCO is useful in monitoring the treatment of carbon monoxide poisoning. Confirmation of CO poisoning is based on detecting carboxyhemoglobin levels above 3%; in smokers, levels above 10% are considered significant.