Rasburicase induced severe hemolysis and methemoglobinemia in a Caucasian patient complicated by acute renal failure and ARDS.

Rasburicase is a recombinant urate-oxidase enzyme and is a very important medication for tumor lysis syndrome. Methemoglobinemia and hemolysis are known side effects of rasburicase that result from oxidative stress caused by hydrogen peroxide, a byproduct generated during the breakdown of uric acid to allantoin. Patients with G6PD deficiency have a decreased tolerance to oxidative stress and are therefore at a greater risk of hemolysis and methemoglobinemia with rasburicase. Our patient is a 56-year-old Caucasian male with a recent diagnosis of grade 2-3a non-Hodgkin's lymphoma who presented to our emergency department with shortness of breath and dark discoloration of urine. Patient was discharged 36 hours ago from our hospital after he was given a first course of R-CHOP regimen and a dose of rasburicase. On further evaluation, patient was found to have severe anemia with hemolytic picture, hyperkalemia and acute kidney injury. He also had a discrepancy of the transcutaneous saturation (75%) and the saturation in an arterial blood gas value (99%). His methemoglobin level was found to be 11.9%. We were aware that methylene blue is a contraindication in patients with G6PD deficiency but considering patient being Caucasian and low risk for it and his deteriorating respiratory condition, it was decided to offer the treatment and patient received 1 dose of methylene blue which failed to improve his methemoglobinemia. He was also given vitamin C and 8 units of packed red blood cell throughout his stay in the hospital. Patient's hospital course was complicated by ARDS needed to be on mechanical ventilation support for 4 days and acute renal failure secondary to pigment nephropathy and acute tubular necrosis which required a hemodialysis support. Even if rasburicase induced methemoglobinemia and hemolysis are not very common complications, clinicians who prescribe and follow patients should detect this serious complication early and manage it accordingly. Our case can be used as a reminder that patients should be followed closely and given the right instructions on discharge to treat these complications which are associated with severe consequences. It is also vital to assume a diagnosis of G6PD deficiency until proven otherwise in a patient who presents with rasburicase induced hemolysis and avoid administration of methylene blue even if the patient is from a low risk ethnicity for G6PD as in our patient.