A case of methemoglobinemia due to antifreeze intoxication in a 15-year-old girl

Methemoglobinemia, although rare, can lead to severe cyanosis and may become life-threatening if not managed properly.Here, we report a case of a 15-year-old girl with acquired methemoglobinemia due to antifreeze poisoning.She was brought to the emergency department following a seizure, presenting with cyanosis and altered mental status.Her initial oxygen saturation was critically low (80%), necessitating endotracheal intubation and transfer to our hospital for advanced care.Upon initial venous blood gas analysis with CO-oximetry evaluation in our emergency department, a significantly elevated methemoglobin level of 72.3% was identified alongside severe lactic acidosis (10.8 mmol/L).Together with aggressive management-including fluid resuscitation, administration of vasoactive agents, and mechanical ventilator support-intravenous methylene blue was given twice, which successfully reduced the serum methemoglobin level to 2.7%.Remarkably, within 12 hours of the initial event, the patient fully recovered.This case highlights the critical importance of a timely diagnosis and prompt, appropriate management of acquired methemoglobinemia.