Systematic Review of Methemoglobinemia in Acetaminophen Poisoning

• Published in: QJM : An International Journal of Medicine 2022-09, Vol.115 (9), p.575-581
• Main Authors: Sahu, Kamal Kant, George, Susan V, Siddiqui, Ahmad Daniyal
• Format: Article
• Language: English
• ISSN: 1460-2725; 1460-2393
• DOI: 10.1093/qjmed/hcaa174

Acetaminophen (N-acetyl-para-aminophenol, paracetamol, (APAP) toxicity is one of the commonly encountered poisonings by emergency physicians. Methemoglobinemia is an uncommon association and rarely seen in APAP poisoning. Retrospective analysis of all the published reports on APAP induced methemoglobinemia from 1968 to 2019. In total there were 14 cases with 9 females and 6 males. The median age of the study cohort was 59 years. The most common presenting feature was altered mentation (9 patients) followed by cyanosis (3 patients). The intent of consumption was therapeutic (7 cases) versus suicidal (5 cases) attempt.In most cases, the dose of APAP consumption was not known. Aspirin, sulfasalazine, benzocaine spray, nitrate preservative, contaminated water, detergents, etc. where the other agents consumed by the patients in addition to APAP before developing methemoglobinemia. The median MethHb level of the study cohort was 15.85% Patients were treated with NAC, hemodialysis, methylene blue, and ascorbic acid and CRRT in various combinations. Full recovery was seen in 9 patients while 4 patients died. APAP toxicity is a well-known and common entity with multiple sequelae that presents with a variable spectrum of mild to fulminant multiorgan failure. Awareness of non-classical presentations like methemoglobinemia is essential to ensure timely intervention.