A blue blood toddler– a case report of methemoglobinemia and literature review

Abstract

Background: Methemoglobinemia (MetHb) is a rare and potentially life-threatening condition caused by oxidation of ferrous hemoglobin (Fe2+) to the ferric (Fe3+) state, making it incapable of binding oxygen and resulting in cyanosis and tissue ischemia. Case presentation: This case presentation describes a 1-year-old boy who developed sudden cyanosis and reduced consciousness disorder. An initial assessment showed decreased oxygen saturation (SpO2 85%) despite oxygen therapy, while point-of-care venous blood gas (VBG) analysis assessed high rates of MetHb (72.7%). Methylene blue and ascorbic acid were administered, resulting in in rapid clinical recovery and normalized VBG test results. The trigger for this condition was not identified, however the most likely cause of poisoning was attributed to food oxidants. Conclusion: Starting from the description of a clinical case, this paper discusses the causes and mechanisms of possible poisoning and reviews recent guidelines for methemoglobinemia management.