Dapsone-induced methemoglobinemia in immune thrombocytopenia: A case report

Abstract

ITP is a bleeding disorder which is not associated by a systemic disease caused by low platelet count or thrombocytes. However, use of dapsone is limited by adverse effects such as methemoglobinemia, reticulocyte increase, hemolysis, hemoglobin decrease, red cell life span shortened, agranulocytosis, anemia, leukopenia, and pure red cell aplasia. This report relates to an incident to methemoglobinemia after administration of dapsone as the second line agent for treatment of ITP in a tertiary care hospital. A 46-year-old male, with a case of immune thrombocytopenia and a family history of aplastic anemia in mother. Now presented with high grade fever associated with generalized weakness, cough with expectoration and shortness of breath and decreased urine output. He was admitted for further management. Initial laboratory investigations were done. Blood and urine cultures were sent. His arterial blood gas showed elevated methemoglobin (18.2). Peripheral smear revealed microcytic hypochromic anemia with polychromatophils, microspherocytes, and relative neutrophilia. Urine culture showed Escherichia coli and blood culture was sterile. Serum electrolytes were sent. He had elevated international normalized ratio (INR) value (5.93). Warfarin and dapsone were withheld.