Tumor Lysis Syndrome

Tumor lysis syndrome (TLS) is an oncologic emergency caused by rapid destruction of malignant cells. When many cells rupture at once, their intracellular contents enter the bloodstream faster than the kidneys can clear them. Potassium leaves lysed cells and produces hyperkalemia, which can trigger fatal dysrhythmias before kidney failure is obvious. Phosphate is also released in large amounts. It binds circulating calcium, causing hyperphosphatemia and secondary hypocalcemia. The resulting low calcium may produce paresthesias, tetany, seizures, or dysrhythmias. Nucleic acids are metabolized through xanthine into uric acid. Uric acid can precipitate within renal tubules, especially when urine flow is poor. Calcium-phosphate deposition also injures the kidneys and, in current practice with widespread uric acid–lowering therapy, is a predominant cause of TLS-associated acute kidney injury (AKI). TLS usually develops during treatment or within 7 days after cytotoxic therapy begins. It may also occur before therapy in highly proliferative cancers, particularly Burkitt lymphoma or acute leukemia with a very high white blood cell count. A patient who has not yet received chemotherapy can still have TLS.