Severe acute haemolytic anaemia associated with severe methaemoglobinaemia in a G6PD-deficient man.

Methaemoglobin is a form of haemoglobin in which the ferrous (Fe2+) ion contained in the iron-porphyrin complex of haem is oxidised to its ferric (Fe3+) state. Methaemoglobinaemia, the presence of methaemoglobin in the blood, is most commonly treated with methylene blue. However, methylene blue cannot be used in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency as it is ineffective in such patients and it can worsen G6PD deficiency haemolysis. We report the case of a 30-year-old man who presented with clinical features of G6PD deficiency-associated haemolysis and was found to have severe methaemoglobinaemia (35%). He was administered blood transfusions and intravenous ascorbic acid. His methaemoglobinaemia resolved within 24 hours. This case demonstrates the successful management of a patient with severe methaemoglobinaemia in the setting of G6PD deficiency haemolysis. Emergency physicians should be aware of the possible co-occurrence of severe methaemoglobinaemia in a patient with G6PD deficiency haemolysis.