title: Acute visual loss following dapsone-induced methemoglobinemia and hemolysis.
abstract: OBJECTIVE
  While methemoglobinemia is a possible complication of chronic dapsone therapy or of acute overdose, serious adverse manifestations related to methemoglobin formation remain rare. We present an unusual case with severe ischemic retinal injury.
  
  
  METHODS
  A 30-year-old African woman presented with a sudden decrease of visual acuity secondary to retinal ischemia. She was chronically treated with dapsone (50 mg/day) for a dermatologic disease and denied any drug overdose. However, the determination of serum dapsone level on admission revealed a largely supratherapeutic concentration (20,044 μg/ml compared with 1-3.5 ± 0.5 μg/ml for therapeutic levels). The methemoglobin level at admission was 32% (sulfhemoglobin 1.2%), with hemoglobin level, 7.4 g/dl, schistocytes count, 2-5%, lactate dehydrogenase level, 580 IU/l, and haptoglobin level, < 10 mg/dl. The patient had both alpha-thalassemia and sickle cell trait. She was treated with methylene blue, vitamin C, and exchange transfusion. There was no improvement in visual symptoms over time.
  
  
  CONCLUSIONS
  In a patient with supratherapeutic serum levels of dapsone, the severity of visual injury was associated with dapsone-induced methemoglobinemia and hemolysis, and perhaps also with some hematologic predisposing factors.
authors: Department of Intensive Care, Cliniques St-Luc, Université catholique de Louvain , Brussels , Belgium.
authors: Delphine
authors: D
authors: Hanuschk
authors: Alexandra
authors: A
authors: Kozyreff
authors: Naima
authors: N
authors: Tafzi
authors: Dominique
authors: D
authors: Tennstedt
authors: Philippe
authors: P
authors: Hantson
authors: Franck
authors: F
authors: Saint-Marcoux
mesh_terms: D000208:Acute Disease; D000328:Adult; D003622:Dapsone / Q000097:blood / Q000506:poisoning*; D062787:Drug Overdose / Q000175:diagnosis / Q000628:therapy; D005260:Female; D006461:Hemolysis / Q000187:drug effects*; D006801:Humans; D007511:Ischemia / Q000139:chemically induced* / Q000175:diagnosis / Q000503:physiopathology; D008708:Methemoglobinemia / Q000097:blood / Q000139:chemically induced* / Q000175:diagnosis / Q000628:therapy; D016896:Treatment Outcome; D014786:Vision Disorders / Q000139:chemically induced* / Q000175:diagnosis / Q000503:physiopathology; D014792:Visual Acuity / Q000187:drug effects*
chemical_list: D003622:Dapsone
keywords: Alpha-Thalassemia; Dapsone; Hemoglobin S trait; Hemolytic anemia; Methemoglobin; Overdose; Retinal ischemia