Tumor Lysis Syndrome: Diagnosis and Management

Definition and Classification

Tumor lysis syndrome (TLS) is classified into laboratory TLS (LTLS) and clinical TLS (CTLS), with laboratory TLS defined by the presence of two or more abnormal serum values, including hyperuricemia, hyperkalemia, hyperphosphatemia, and hypocalcemia, within three days before or seven days after initiation of anticancer therapy, according to the Journal of Clinical Oncology 3
Clinical TLS requires the presence of laboratory TLS plus one or more clinical complications, such as renal insufficiency, cardiac arrhythmias, or seizures, as stated by the Journal of Clinical Oncology 3, 5

Common symptoms of TLS include nausea, vomiting, diarrhea, anorexia, lethargy, edema, fluid overload, and hematuria, as reported by the Journal of Clinical Oncology 3
Severe manifestations may include congestive heart failure, cardiac dysrhythmias, seizures, muscle cramps, tetany, syncope, and possible sudden death, according to the Journal of Clinical Oncology 3

High-grade hematologic malignancies with rapid proliferation rates, such as Burkitt's lymphoma, ALL, and AML, are associated with a higher risk of TLS, as stated by the Journal of Clinical Oncology 1
Pre-existing elevated uric acid levels, pre-existing renal dysfunction, advanced age, and tumor infiltration in the kidney are also risk factors for TLS, as reported by Praxis Medical Insights: Practical Summaries of Clinical Guidelines 4

TLS occurs most frequently in patients with non-Hodgkin lymphoma (NHL) and other hematologic malignancies, with laboratory TLS found in 42% of patients and clinically significant symptoms in 6%, according to the Journal of Clinical Oncology 3
In pediatric NHL patients, 4.4% developed TLS, with higher rates in Burkitt's lymphoma or B-ALL (8.4%), as reported by the Journal of Clinical Oncology 3

The diagnosis of TLS is based on laboratory findings, including serum levels of uric acid, potassium, phosphorus, calcium, and creatinine, and clinical manifestations, such as renal insufficiency, cardiac arrhythmias, and seizures, as stated by the Journal of Clinical Oncology 1, 4

High-risk patients should receive hydration and rasburicase, while intermediate-risk patients should receive hydration plus either allopurinol or rasburicase, and low-risk patients should receive hydration and oral allopurinol, as recommended by Haematologica 6, 2
Aggressive hydration is fundamental to prevention and management of TLS, promoting excretion of uric acid and phosphate by improving intravascular volume, renal blood flow, and glomerular filtration, as reported by the Journal of Clinical Oncology 5
Rasburicase is a recombinant urate-oxidase enzyme that converts existing uric acid to allantoin, which is 5-10 times more soluble in urine than uric acid, as stated by Haematologica 2

Patients at risk should be monitored for at least 24-72 hours after initiation of therapy, with laboratory parameters, such as uric acid, potassium, phosphorus, calcium, and creatinine, checked frequently based on risk level, as recommended by the Journal of Clinical Oncology 3, 4
Urine output should be monitored closely to ensure adequate hydration, as reported by the Journal of Clinical Oncology 5