Methemoglobinemia due to Hemolysis Secondary to Infection in a Child: A Case Report

Methemoglobinemia is a rare condition characterised by hypoxic state manifesting as headache, nausea, fatigue, and confusion. We report a 2-year-old boy presenting with fever and cough for 7 days with an episode of hypoxia as the saturation declined and did not improve on face mask oxygenation. On further evaluation, acute intravascular hemolysis was established following decreased haemoglobin level, increased levels of lactate dehydrogenase, and unconjugated bilirubin in the setting of documented infection. Assessment of arterial blood gas showed a significantly raised saturation gap and detection of methemoglobin confirmed the diagnosis. He was managed conservatively with packed red blood cells transfusion following which hypoxia was corrected. Methemoglobinemia as a result of hemolysis can be a non-cardio-respiratory cause of hypoxia and inciting aetiology needs to be addressed.