Methemoglobinemia
Methemoglobinemia can be due to certain medications, chemicals, or food or it can be inherited from a person's parents. Substances involved may include benzocaine, nitrates, or dapsone. The underlying mechanism involves some of the iron in hemoglobin being converted from the ferrous [Fe2+] to the ferric [Fe3+] form. The diagnosis is often suspected based on symptoms and a low blood oxygen that does not improve with oxygen therapy. Diagnosis is confirmed by a blood gas.
Methemoglobinemia-2