Methemoglobinemia in the Setting of Hemolysis: A Case Report Suggesting Reflex Lab for Patients with Oxygen Saturation Gap for Early Detection and Diagnosis

Methemoglobinemia typically presents as functional anemia and hypoxemia. It is often recognized by a discordance between the pulse oximeter reading and the oxygen saturation measured on arterial blood gas. Methemoglobinemia can be inherited or acquired, with some commonly-used medications recognized as causative agents. In patients with hemolytic anemia such as in glucose-6-phosphate dehydrogenase deficiency, hemolysis may be the main clinical presentation, with acquired methemoglobinemia after exposure to oxidizing agents. We present a case report of methemoglobinemia in the setting of hemolysis, with a new approach to coordinate with laboratory services to create a reflex lab to test for methemoglobinemia under certain conditions. This may improve time to recognition and treatment for patients with methemoglobinemia, as patient presentation as well as SpO2 and PaO2 discordance may be missed by less experienced providers.