Dapsone-induced methemoglobinemia: "Saturation gap"-The key to diagnosis

Abstract

Two cases of Acquired Methemoglobinemia are presented. The significance of a high index of suspicion for diagnosisis emphasized, especially in the presence of a “saturation gap”. The various causes of acquired methemoglobinemia are enumerated and the management reviewed.

SARS-CoV-2 infection, pulse oximetry, and interpretive caveats

“…Methaemoglobinemia should be suspected in the presence of cyanosis, refractory hypoxaemia (despite oxygen supplementation), and a ‘saturation gap’. 3 …”

“…Methaemoglobinemia should be suspected in the presence of cyanosis, refractory hypoxaemia (despite oxygen supplementation), and a 'saturation gap'. 3 Treatment is primarily guided by the clinical manifestations as well as the methaemoglobin level. The causative agent must be discontinued in all cases.…”

Three doses of dapsone causing methemoglobinemia in leprosy: A report of two cases

“…cratic as well as pharmacologically expected side effects of the drug including methemoglobinemia which is a rare, dose-dependent adverse effect and has usually been described in the literature post long-term drug usage over weeks to months or with high daily doses (2 mg/kg). [1][2][3] We hereby report two rare cases of Hansen's disease who developed dapsone-induced methemoglobinemia within only 3 days of therapy.…”

A case of DAPSONE INDUCED METHEMOGLOBINEMIA

“…One is cytochrome b5 reductase pathway and the other is nicotinamide adenine dinucleotide phosphate (NADPH) dependent MetHb reductase, requiring a cofactor methylene blue or riboflavin for activation [2]. Clinical presentation is directly related to the levels of methemoglobin, Table 1 [3]. The purpose of presenting this case is to emphasize the importance of considering rare causes of cyanosis in the presence of normal cardio-respiratory systems.…”