Rasburicase has been approved for use in both children and adults, but there is more evidence for the use in children. Rasburicase has a black-box label for patients with anaphylaxis, methemoglobinemia, hemolysis, and hemoglobinuria, and there is a recommendation to check G6PD deficiency before use in high-risk patients.30
TLS Treatment
Alkalinization. Alkalinization of urine is controversial in the management of TLS. Urine alkalinization increases uric acid solubility but causes hyperphosphatemia and decreases calcium phosphate solubility, which can then deposit in the kidney once cancer treatment starts. Of note, hyperphosphatemia is much more difficult to correct than high levels of uric acid, and there are no clinical trials proving the superiority of urine alkalinization over normal saline.
Normalization of electrolytes. Electrolyte abnormalities should be corrected to avoid arrhythmias and seizures. Phosphorus levels >6.5 mg/dl (2.1 mmol/L) should be managed by restricting phosphorus intake, and by the use of phosphate binders (calcium acetate, calcium carbonate, sevelamer, lanthanum, or aluminum hydroxide). Aluminum hydroxide should be avoided in patients with renal insufficiency. In severe cases of hyperphosphatemia, dialysis should be considered.
Symptomatic hypocalcemia should be treated with calcium gluconate if changes are present on the electrocardiography (ECG). Hypocalcemia in the presence of hyperphosphatemia should be treated only in patients with tetany or cardiac arrhythmias; otherwise, hypocalcemia should not be treated until hyperphosphatemia has been corrected.
In cases of hyperkalemia, patients should be placed on a cardiac monitor and stabilized with calcium gluconate; kayexalate should be administered to reduce total body potassium. Other interventions, such as intravenous insulin given with dextrose, sodium bicarbonate, and albuterol, have a temporary effect on hyperkalemia and can be used as adjunct treatments in patients with severe hyperkalemia (>7). Hemodialysis should be strongly considered in severe cases of hyperkalemia, particularly in patients with persistently elevated potassium levels despite other treatments.
Back to the Case
Our patient was started on IVFs with close monitoring of his urine output. He was considered intermediate risk for developing TLS. Allopurinol, renally dosed, was administered for two days prior to initiating treatment with rituximab plus chemotherapy. His chemistry panel was monitored daily and he did not develop any form of TLS.
Bottom Line
TLS is a common oncology emergency in patients with hematologic malignancies. Preventative measures include starting IVF prior to cancer treatment, and administering allopurinol and/or rasburicase to patients at risk of developing TLS. Treatment should include normalizing electrolytes to avoid arrhythmias and seizures.
Dr. Akwe is assistant professor of medicine at the Emory University School of Medicine and a clinical instructor of medicine at the Morehouse School of Medicine, both in Atlanta. Dr. Smith is an assistant director for education in the division of hospital medicine at Emory. Both work as hospitalists at the Atlanta VA Medical Center.