On the basis of strong clinical evidence, tumor lysis syndrome (TLS) is the most common life-threatening emergency in childhood malignancies that occurs when cancer cells break down, either spontaneously or after initiation of cytotoxic chemotherapy, and release their intracellular contents into the bloodstream. (2)(3)(4)(5)(7) The intracellular release of uric acid, potassium, and phosphorous, which, under normal physiologic conditions are excreted in the urine, can lead to hyperuricemia, hyperkalemia, hyperphosphatemia, and hypocalcemia. Based on strong clinic evidence, these metabolic derangements increase the risk of severe complications, including acute kidney injury, cardiac arrhythmias, seizures, and even death. (2)(3)(4)(5)(7) TLS most commonly occurs in rapidly dividing hematologic malignancies that have both a high tumor proliferation rate and a large tumor burden at presentation. This most commonly occurs with acute lymphoblastic leukemia, Burkitt leukemia/lymphoma, and diffuse large B-cell lymphoma. (4)(5). Burkitt lymphoma/ leukemia is well-known to have a very high tumor proliferation rate and can outgrow its own metabolic capacity, resulting in spontaneous and severe tumor lysis at presentation. On the basis of strong evidence, TLS management centers on maintaining a high index of suspicion, identifying patients at higher risk for TLS, and employing an aggressive prophylactic strategy to prevent the laboratory and clinical manifestations of TLS. (2)(7) Based on expert opinion, any pediatric patient who presents with concerns for a new malignancy should undergo up-front measurement of serum uric acid, lactate dehydrogenase, potassium, phosphorus, and calcium levels, as well as serum creatinine levels, along with consideration of aggressive volume repletion and/or expansion to optimized renal function. (2)(3)(4)(5) Based on strong evidence, all pediatric patients at intermediate or high risk for TLS should continue to receive intravenous hydration to optimize kidney function and minimize acidosis. (7) This is often achieved with hyperhydration (without potassium) to maintain a urine output of 3 to 5 mL/kg per hour. Close monitoring for fluid overload and third spacing is important. Close monitoring of laboratory TLS is also a key strategy through serial measurements of serum uric acid, potassium, phosphorus, calcium, and creatinine levels. Prophylaxis (with allopurinol) and treatment of hyperuricemia are aimed at maintaining normal serum levels of uric acid. Based on strong evidence, patients who develop signs or symptoms of TLS require prompt interventions relying on a multidisciplinary approach with the support of pediatric nephrologists and intensive care physicians to rapidly treat any TLS-induced metabolic derangements and maximize outcomes. © 2020 American Academy of Pediatrics. All rights reserved.
