A 53-year-old man presented to the emergency department of the hospital, after a syncopal episode. Patient history The patient is a regular smoker and recreational drug user and had taken heroin, cannabis, and benzodiazepine during that week. He has a history of glucose-6-phosphate dehydrogenase (G6PD) deficiency. Physical examination Has gray pallor and is dyspnoeic at rest (respiratory rate 23 breaths per minute). Oxygen saturation: 70% on 100% inspired oxygen His blood sample, which showed anemia (haemoglobin54 g/L; normal 130–180 g/L), was chocolate brown (figure).
Arterial blood gas analysis showed pH 7·40 (7·35–7·45) and methemoglobin 26% (<2%). What is the most likely cause? Thalassemia Methemoglobinemia Drepanocytosis Carbon monoxide poisoning *This case is from Docplexus Editorial Team for educative purpose only. Source: Lancets
