Tumor Lysis Syndrome (TLS)

Tumor lysis syndrome develops when malignant cells die rapidly, either spontaneously or after cytotoxic treatment. Their intracellular contents enter the circulation faster than the kidneys can clear them. Potassium rises directly from cell contents and can trigger conduction abnormalities and lethal dysrhythmias. Phosphate also rises. It binds circulating calcium, lowering the ionized calcium concentration and allowing calcium-phosphate precipitation in tissues, including the kidneys. Nucleic acids are metabolized to uric acid; uric acid can crystallize in renal tubules, obstruct flow, and worsen acute kidney injury. Reduced kidney function then makes every electrolyte abnormality harder to correct. The pattern to recognize is hyperkalemia, hyperphosphatemia, hyperuricemia, hypocalcemia, and a falling urine output. The most immediate threat is usually potassium-related cardiac instability; symptomatic hypocalcemia can cause tetany, seizures, or dysrhythmia.