TLS is a constellation of metabolic abnormalities that usually occur within the first 3 to 5 days of starting chemotherapy. Clinicians must be aware that hydration alone can cause cell lysis, placing patients undergoing a diagnostic oncologic work up at risk for TLS. In rare cases, TLS can occur spontaneously. Patients with non-Hodgkin lymphoma and T-cell acute lymphoblastic leukemia have the highest risk of TLS due to the bulky lymphadenopathy and leukocytosis often accompanying these diseases.

Hyperuricemia, hyperphosphatemia with associated hypocalcemia, and hyperkalemia are the laboratory abnormalities seen in patients with TLS. The intracellular ions potassium and phosphate are released when cells are lysed by chemotherapy. Hyperuricemia occurs when DNA building blocks (namely the purines, guanosine and adenosine) found within tumor cell nuclei are released and degraded to uric acid. A compensatory increase in urinary excretion of uric acid and phosphate occurs. Depending on the size of the tumor burden, the kidneys may be overwhelmed by the amount of intracellular debris that needs to be excreted. Uric acid is soluble at physiologic pH, but in the acidic conditions commonly seen with a high cell turnover rate and possible renal hypoperfusion, urate crystals can form in the renal collecting system. Calcium phosphate deposits can also precipitate in the renal tubules. These can lead to renal failure, placing the patient at risk for further hyperkalemia and life-threatening cardiac arrhythmias. The best treatment for TLS-associated renal failure is prevention. Hydration, urinary alkalinization, and inhibition of uric acid production are the standard preventative interventions for TLS. Intravenous fluids usually run at high flow rates (3 L/m²/day, approximately 2 times maintenance) with sodium bicarbonate infused in a separate line, adjusting the infusion rate to maintain the urine pH between 7 and 8. Uric acid precipitates at a urine pH of <7 and calcium/phosphate stones may form in urine with a pH >8. Urine pH should be tested with each void, and adjustments to the rate of bicarbonate infusion should be made accordingly.