A Diagnostic Dilemma: What Not to Miss in Methaemoglobinaemia

Methaemoglobinaemia is a rare disorder in which haemoglobin loses its ability to deliver oxygen to tissues due to oxidation of haem iron. It may be congenital or acquired, most commonly secondary to medication. Patients present with apparent hypoxia unresponsive to oxygen therapy, which can be life-threatening at higher levels. Here we describe a case of dapsone-induced methaemoglobinaemia, which was initially overlooked due to possible sinister pathologies, leading to extensive investigations and repeated admissions, underscoring the importance of careful ABG interpretation and medication review.