What is the most appropriate management for a patient with lymphoma receiving B-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) chemotherapy who presents with hyperkalemia and hypocalcemia?

Management of Tumor Lysis Syndrome in Lymphoma Patients Receiving R-CHOP

The most appropriate initial management is aggressive IV hydration (2-3 L/m²/day), not rasburicase, lasix, or thiazide diuretics. The combination of hyperkalemia and hypocalcemia in this clinical context is pathognomonic for tumor lysis syndrome (TLS), and aggressive IV hydration is the cornerstone of management according to multiple guideline societies 1.

Clinical Recognition

• This patient has tumor lysis syndrome, characterized by the release of intracellular contents from rapidly lysing tumor cells during chemotherapy 1
• The classic laboratory findings include hyperkalemia (from intracellular potassium release), hypocalcemia (from calcium-phosphate precipitation due to hyperphosphatemia), and hyperphosphatemia (from intracellular phosphate release) 1
• Hyperuricemia may or may not be present, but is not mentioned in this case 1

Primary Management Strategy

Aggressive IV hydration is the definitive first-line intervention, with the goal of maintaining urine output of at least 100 mL/m²/hour 1. This facilitates the excretion of potassium, phosphate, and uric acid through the kidneys 1.

• The recommended hydration rate is typically 2-3 L/m²/day 1
• This approach is endorsed by the National Comprehensive Cancer Network, American College of Physicians, and European Society for Medical Oncology as the primary intervention 1

Why Not the Other Options?

Rasburicase (Option C) is NOT the most appropriate initial management because:

• Rasburicase is specifically indicated for documented hyperuricemia, which is not mentioned in this case 1
• It works by converting uric acid to allantoin, addressing only one component of TLS 2
• Without documented hyperuricemia, rasburicase is not the priority intervention 1

Lasix/Furosemide (Option A) is contraindicated because:

• Loop diuretics can worsen electrolyte abnormalities and precipitate uric acid in renal tubules
• They reduce intravascular volume, which is counterproductive when the goal is to maintain high urine output through hydration

Thiazide diuretics (Option B) are contraindicated because:

• They can worsen hypocalcemia by increasing urinary calcium excretion
• They reduce effective circulating volume, opposing the goal of aggressive hydration

Additional Management Considerations

After initiating aggressive IV hydration, additional interventions may be necessary based on severity 1:

• For severe hyperkalemia: Consider calcium gluconate (for cardiac membrane stabilization), insulin/dextrose, sodium polystyrene sulfonate, or dialysis 1
• For symptomatic hypocalcemia: Cautious calcium replacement may be necessary, though calcium should generally be avoided unless the patient is symptomatic, as it can worsen calcium-phosphate precipitation 1
• Close monitoring: Electrolytes and renal function require frequent monitoring 1

Prevention for Future Cycles

• Prophylactic measures should be implemented before subsequent chemotherapy cycles, including aggressive IV hydration and consideration of rasburicase prophylaxis for high-risk patients 1
• Corticosteroid pre-phase treatment (prednisone 100 mg daily for 5-7 days) should be considered for patients with high tumor burden to prevent TLS in future cycles 1, 3

Common Pitfall

The most critical error would be administering rasburicase without first ensuring adequate hydration and urine output, or using diuretics that could worsen the metabolic derangements and precipitate acute kidney injury.