Mixed methemoglobinemia, congenital and acquired

• Autor(a) principal: Murinello, António
• Data de Publicação: 2023
• Outros Autores: Bicho, Manuel, Estrela Inácio, Rosa, Loureiro, Maria Conceição
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: https://revista.spmi.pt/index.php/rpmi/article/view/2022
• topic: Meta-hemoglobinemia; azul de metileno; anilina; redutase do citocrómio-b5; Methaemoglobinaemia; methylene blue; aniline; cytochrome-b reductase

The   authors present  a case of acute methaemoglobinaemia of mixed aetiology - congenital and acquired. Excessive cutaneous absorption of aniline dye was the causal factor, but an associated moderate defect in cytochrome-b reductase as well as a glucose-6-phosphate dehydrogenase (G6PD) deficiency aggravated the clinicai course of the disease. Therapy with methylene blue was effective, but it caused haemolytic jaundice, probably because of the concomitant glucose-6-phosphate deficiency or because of the haemolytic action of the toxin and/ or possible hemolytic action of methylene blue. A review of the erythrocyte enzymatic mechanisms that convert methaemoglobin to haemoglobin, clinicai symptoms, aetiology of acute methaemoglobinaemia, referring particularly to aniline as a toxic acquired cause, and to the deficiency of cytocrome-b_, reductase as the most frequent cause of congenital aetiology, is presented. The  benefit of methylene blue therapy is considered as well as associated side-effects, particularly in the presence of concomitant G6PD deficiency. The enzymatic study of relatives is very important for the prevention of similar episodes.