Tumor lysis syndrome
Formal Definition
A potentially life-threatening metabolic emergency caused by the rapid lysis of malignant cells releasing intracellular contents into the bloodstream, resulting in hyperuricemia, hyperkalemia, hyperphosphatemia, and hypocalcemia; occurs spontaneously in high-burden hematologic malignancies or is triggered by chemotherapy initiation.
How It's Used on the Ward
"TLS" or "tumor lysis" — the feared metabolic crash that follows chemo in high-tumor-burden leukemia or lymphoma.
Example
""Newly diagnosed Burkitt lymphoma starting first cycle of RCHOP: high TLS risk. Aggressive IV hydration, allopurinol started 48 hours before chemo, checking BMP and uric acid every 6 hours for the first 48 hours post-chemo. If uric acid spikes, rasburicase is ready.""
Clinical Context
Cairo-Bishop criteria: two or more of: uric acid >8, potassium >6, phosphorus >4.5, or calcium <7 (or 25% change from baseline). Clinical TLS = lab TLS + organ dysfunction (renal failure, arrhythmia, seizure). Prophylaxis: aggressive IV hydration (200–300 mL/hr), allopurinol (XO inhibitor). High-risk patients (Burkitt, ALL, large-cell lymphoma with high LDH): rasburicase (recombinant urate oxidase) — rapidly degrades uric acid, contraindicated in G6PD deficiency. Most dangerous: hyperkalemia (arrhythmia) and acute kidney injury. Monitoring every 4–8 hours during highest-risk period.