Favism induced methemoglobinemia in a G6PD deficient male with a subsequent hemolytic cascade, a therapeutic challenge: case report and review of literature

Abstract

We report a 56-year-old man with methemoglobinemia and hemolytic anemia, secondary to fava bean ingestion. Methylene blue administration worsened the hemolysis as he was G6PD deficient but not diagnosed before. We have discussed the mechanism of hemolysis in such patients and the management of such cases.Hemolytic anemia, a form of anemia that causes premature rupture of erythrocytes, accounts for five percent of anemias. 1 Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a well-known cause of hemolysis and currently affects around 400 000 000 individuals globally. It has a notable prevalence in African, Asian, and Mediterranean countries. 2 Favism is a common trigger of oxidative stress in G6PD deficient people, which can lead to hemolysis. Additionally, fava bean ingestion can cause methemoglobinemia. 3 Methemoglobin is an abnormal variation in the hemoglobin in which the ferrous (Fe2 + ) iron in heme is oxidized to the ferric (Fe3 + ) state. The condition is usually acquired, secondary to oxidative stress in the body such as favism or infections, but can rarely be congenital. 4 The first-line treatment for methemoglobinemia is methylene blue. However, in G6PD deficient patients, methylene blue can potentiate hemolysis because of its oxidative effects. 3 It is vital to take a detailed history of patients presenting with hemolysis to identify the potential causes and avoid any additional oxidative stress.

Acute hemolysis and methemoglobinemia secondary to fava beans ingestion in a patient with G6PD deficiency

“…Among these cases, 1 patient received methylene blue before knowing that he is G6PD deficient, which resulted in worsening hemolysis. [10] Two other patients were treated with vitamin C only. [11,12] In our case, the level of MetHb was mildly elevated and the patient was asymptomatic and was not cyanosed.…”

“…All 8 patients were male with median age of 18 years (1–56) and MetHb level ranging from 3.5% to 35%. Among these cases, 1 patient received methylene blue before knowing that he is G6PD deficient, which resulted in worsening hemolysis [10] . Two other patients were treated with vitamin C only [11,12] .…”