What can prevent hyperuricemia and subsequent tumor lysis syndrome (TLS) in a patient post B cell lymphoma chemotherapy with symptoms of nausea, vomiting, hyperkalemia, hypocalcemia, and hyperphosphatemia?

Rasburicase Prevents Tumor Lysis Syndrome in High-Risk B-Cell Lymphoma Patients

The correct answer is D. Rasburicase, which should have been administered prophylactically before chemotherapy to prevent this presentation of tumor lysis syndrome (TLS). 1

Why Rasburicase is the Answer

This patient has classic clinical TLS with all the hallmark metabolic derangements:

• Hyperkalemia (K 6 mmol/L)
• Hypocalcemia
• Hyperphosphatemia
• Acute kidney injury (Urea 570)
• Nausea and vomiting 1

B-cell lymphoma patients receiving chemotherapy are at high risk for TLS and require prophylactic rasburicase, not allopurinol. 1 The guidelines are unequivocal: for high-risk patients (which includes aggressive lymphomas like B-cell lymphoma with bulky disease), rasburicase combined with aggressive hydration is the recommended prophylactic strategy. 1, 2

Why Each Answer is Right or Wrong

Rasburicase (Correct)

• Rasburicase converts existing uric acid to allantoin, which is 5-10 times more soluble than uric acid, providing immediate reduction of hyperuricemia. 1
• In a randomized trial comparing rasburicase to allopurinol in high-risk hematologic malignancies, rasburicase achieved significantly lower uric acid levels (p<0.001) and reduced dialysis requirements from 16% to 2.6%. 1
• Should be given at 0.20 mg/kg/day IV over 30 minutes, starting at least 4 hours before chemotherapy. 2, 3

Allopurinol (Incorrect - Answer B)

• Allopurinol only prevents NEW uric acid formation by blocking xanthine oxidase—it does NOT eliminate pre-existing uric acid. 1
• In high-risk patients, allopurinol is inferior to rasburicase because TLS develops too rapidly for allopurinol's preventive mechanism to be effective. 1
• The guidelines explicitly state that high-risk patients require rasburicase, not allopurinol. 1, 2

Furosemide (Incorrect - Answer C)

• Loop diuretics like furosemide are adjunctive measures to maintain urine output ≥100 mL/hour during hydration, but they do NOT prevent TLS. 1, 2
• Furosemide addresses volume management but does nothing to prevent the metabolic catastrophe of massive tumor cell lysis. 1

Thiazide (Incorrect - Answer A)

• Thiazides have no role in TLS prevention or management. 1
• They can actually worsen hyperuricemia and are contraindicated in this setting.

The Prevention Algorithm for High-Risk Patients

High-risk factors in this case: 1

• B-cell lymphoma (high-grade hematologic malignancy)
• Receiving intensive chemotherapy
• Likely elevated LDH (common in aggressive lymphomas)

Prophylactic regimen that should have been given: 1, 2

1. Start aggressive IV hydration 48 hours before chemotherapy

   • Target: 2-3 L/m²/day
   • Goal urine output: ≥100 mL/hour 1

2. Administer rasburicase 0.20 mg/kg/day IV

   • Begin at least 4 hours before chemotherapy
   • Continue for 3-5 days 2, 3

3. Monitor electrolytes every 6-12 hours

   • Uric acid, potassium, phosphate, calcium, creatinine 2

Critical Pitfalls to Avoid

• Never use allopurinol alone in high-risk patients—this is inadequate prophylaxis and leads to preventable TLS. 1
• Never alkalinize urine when using rasburicase—this increases calcium-phosphate precipitation risk without benefit since rasburicase rapidly degrades uric acid. 1, 4
• Never give rasburicase to patients with G6PD deficiency—this causes severe hemolysis. 3
• Never delay rasburicase administration—TLS can develop within hours of chemotherapy initiation. 1, 5

Evidence Quality Note

The recommendation for rasburicase over allopurinol in high-risk patients comes from Level 1 evidence including randomized controlled trials 1 and is supported by multiple international consensus guidelines from the American Society of Clinical Oncology and European Hematology Association. 1, 2 The superiority of rasburicase in preventing dialysis (2.6% vs 16%) represents a clinically meaningful reduction in morbidity and mortality. 1