A case of hemolysis and methemoglobinemia following amyl nitrite use in an individual with G6PD deficiency

A 34-year-old man presented feeling generally unwell with dark urine 3 days after inhaling amyl nitrite. His initial heart rate was 118/min, blood pressure 130/85 mmHg, O₂ saturation 85% on 15 L/min oxygen, and Glasgow coma score 15. He was pale, with clear chest sounds on auscultation. His hemoglobin was 60 g/L, bilirubin 112 μM, and methemoglobin concentration 6.9% on an arterial blood gas. Amyl nitrite-induced hemolysis and methemoglobinemia were diagnosed. Methylene blue was not administered because of the relatively low methemoglobin concentration and the possibility of inducing further hemolysis. He was subsequently confirmed as having glucose-6-phosphate dehydrogenase deficiency, which had originally been diagnosed in childhood. Amyl nitrite toxicity may include concurrent methemoglobinemia and hemolysis. Administration of methylene blue for clinically significant methemoglobinemia can induce further hemolysis.