Background: Rasburicase is commonly used in patients with hematologic malignancies for
tumor lysis syndrome prophylaxis and management. Methemoglobinemia is a serious rare adverse effect
of rasburicase, more common in patients with G6PD deficiency. Prompt diagnosis and appropriate
management of this condition can make the difference between successful recovery and significant
morbidity. Here we discuss the link of rasburicase with methemoglobinemia and the pathophysiology
behind increased incidence of this side effect in G6PD deficient patients.
Methods: We report the case of a 73-year-old African American man who developed
methemoglobinemia on rasburicase treatment, who was later confirmed to be G6PD deficient. We
reviewed the literature using Pubmed and Google Scholar using the following key words:
“methemoglobinemia”, “rasburicase”, “urate oxidase”, tumor lysis syndrome”, G6PD deficiency”,
“hemolytic anemia” and “hyperuricemia”.
Results: Rasburicase-induced methemoglobinemia is more common in patients with G6PD deficiency,
and rasburicase is therefore contraindicated in these patients. Clinical presentation includes cyanosis,
pallor, methemoglobin levels of 8-12%, and oxygen saturation gap which is evident from ABG analysis,
though pulse oximetry is normal. Treatment consists of oxygen supplementation, ascorbic acid and
blood transfusion. Importantly, methylene blue is avoided as therapy in G6PD deficiency as it can
worsen the methemoglobinemia.
Conclusion: Rasburicase-induced methemoglobinemia is a serious concern, especially in African-
American patients. It should be considered when clinical signs and symptoms are present. Knowledge of
this side effect is important in early diagnosis and successful management of the condition.