Near-fatal pediatric methemoglobinemia secondary to intentional sodium nitrite ingestion.

Methemoglobinemia is the result of inappropriate oxidation of hemoglobin iron groups, leading to a failure of oxygen transport and delivery, resulting in a clinical state of refractory hypoxia. Methemoglobin levels above 70% are often considered fatal. Acquired methemoglobinemia can be caused by a variety of substances, including sodium nitrite, a commercially available food preservative and color fixative.