Acute methemoglobinemia after a normal diet

• Published in: Journal of medicine and life science Vol. 18; no. 1; pp. 20 - 23
• Main Authors: Lee, Sung Kgun, Kang, Jeong Ho
• Format: Journal Article
• Language: English
• Published: Institute for Medical Science, Jeju National University 30.04.2021
• Subjects: case reports; diet; methemoglobinemia; methylene blue
• ISSN: 2671-4922; 2671-4922
• DOI: 10.22730/jmls.2021.18.1.20

Methemoglobin is generated by the oxidation of ferrous iron to ferric iron within a hemoglobin molecule. Methemoglobin is unable to bind and transport oxygen, resulting in methemoglobinemia, which can lead to fatal tissue hypoxia. The most common cause of methemoglobinemia is poisoning by oxidizing agents such as dapsone, benzocaine, and primaquine. However, methemoglobinemia can also be caused by normal dietary sources. We present two cases of methemoglobinemia that developed after a normal diet in two male patients. In this case report, the patients suddenly developed dyspnea and cyanosis after eating the same meal. They had no history of suspected poisoning, such as the use of drugs, exposure to chemicals, or gas inhalation. Their symptoms did not improve even after a high dose of oxygen was administered; further, an abnormal ‘oxygen saturation gap’ was observed. Because of CO-oximetry, the methemoglobin levels of the patients were 50.0% and 46.6%, respectively. We administered methylene blue (1 mg/kg), and the patients recovered completely without any complications. Emergency physicians should, therefore, be aware that methemoglobinemia can also be caused by normal dietary sources. In addition, if the source and route of contamination are unclear, an epidemiological investigation should be conducted.