Rasburicase-Induced Methemoglobinemia.

Methemoglobinemia occurs as iron in heme is oxidized to its ferric state, resulting in a decreased ability of hemoglobin to bind and release oxygen. Rasburicase is a recombinant urate-oxidase enzyme used in the prevention of tumor lysis syndrome. Methemoglobinemia can occur as a rare complication of treatment with rasburicase, primarily in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency.