Brief Summary of Tumor Lysis Syndrome

Tumor lysis syndrome consists of hyperuricemia, hyperphosphatemia, hyperkalemia, and hypocalcemia in a patient presenting with leukemia or lymphoma, especially those with a very high white blood cell count, Burkitt leukemia/lymphoma, or T-cell leukemia/lymphoma.

Cause:
Tumor lysis can occur prior to the onset of therapy due to spontaneous blast cell breakdown, but more typically occurs after initiating therapy. Tumor lysis syndrome has rarely been reported in children with other solid tumors. In order to prevent acute renal failure, it is essential that tumor lysis be treated aggressively.

Laboratory tests:
A patient with suspected tumor lysis syndrome should have the following laboratory studies performed at the time of presentation: CBC with manual differential, and chemistry panel (to include potassium, creatinine, calcium, phosphorus, and uric acid).

Therapy:

• Therapy for tumor lysis syndrome includes IV hydration at 2 or more times maintenance (~3,000 mL/m2/day), urinary alkalinization, and allopurinol to decrease the formation of uric acid.
• Potassium should not be included in the IV fluid.
• Hydration fluids should include 30 to 40 mEq/L of NaHCO3 to maintain urine pH from 7 to 7.5 in order to facilitate excretion of uric acid and phosphate. Efforts should be made, however, to keep the urine pH below 8, as this promotes formation of calcium-phosphate stones. If phosphorus levels are rising rapidly, amphogel can be added to aid in its excretion.
• Depending on the severity of the metabolic abnormalities, kidney function, uric acid, calcium, phosphorus, and potassium should be assessed every 6 to 8 hours. Frequency can be altered when therapy is started (every 4 hours if necessary), and when laboratory values have stabilized (daily).
• Dialysis is indicated in patients with refractory fluid overload, hyperkalemia, acidosis, or hyperphosphatemia. A pediatric nephrologist should be consulted early in the patient’s course to facilitate dialysis if necessary.
• Rasburicase is a recombinant urate-oxidase enzyme that directly breaks down uric acid (in contrast to allopurinol, which inhibits its formation). It has been shown to be effective in controlling uric acid levels in children and adults with hyperuricemia due to tumor lysis syndrome. Children receiving rasburicase have demonstrated rapid declines in serum uric acid levels, accompanied by a more rapid normalization of kidney function . Patients with hyperleukocytosis and/or impaired renal function should receive rasburicase instead of allopurinol to treat hyperuricemia (0.2 mg/kg IV daily until stable). Those who are treated with rasburicase do not require alkalinization of their urine (but still should receive aggressive hydration without potassium).