A nurse is caring for a 60-year-old patient with non-Hodgkin lymphoma who develops tumor lysis syndrome after starting rituximab. Which nursing intervention should be the highest priority?

The highest priority is aggressive IV hydration with normal saline to maintain urine output and prevent acute kidney injury from uric acid and phosphate crystallization in tumor lysis syndrome. Other interventions (hemodialysis, calcium gluconate, allopurinol) may be needed but are not the immediate priority.

Understanding Tumor Lysis Syndrome (TLS) Pathophysiology
When cytotoxic therapy (like rituximab-containing regimens) rapidly kills malignant cells in hematologic cancers such as non-Hodgkin lymphoma, intracellular contents—potassium, phosphate, and nucleic acids—are released into the bloodstream in massive quantities. Nucleic acids are metabolized to uric acid, leading to hyperuricemia, hyperkalemia, and hyperphosphatemia with secondary hypocalcemia. These metabolic derangements can precipitate acute kidney injury (AKI), cardiac arrhythmias, and multiorgan failure ^[1]. The case report on bendamustine-rituximab in CLL emphasizes that even first-cycle therapy in patients with high disease burden can trigger severe TLS with AKI, underscoring the need for aggressive prophylaxis and close monitoring during early treatment ^[1].

Priority Nursing Intervention: Rationale
The highest priority intervention is aggressive IV hydration with normal saline and strict monitoring of urine output. This approach directly targets the most critical pathophysiologic mechanism of TLS-related renal injury: uric acid and calcium phosphate crystal deposition in renal tubules. Vigorous hydration promotes high urine flow, which mechanically flushes these crystals and dilutes nephrotoxic solutes, thereby preventing or mitigating AKI. Maintaining adequate renal perfusion and urine output also facilitates excretion of potassium and uric acid, reducing the risk of life-threatening hyperkalemia-induced arrhythmias ^[3]. The simulation case on pediatric spontaneous TLS highlights that prompt recognition of hyperkalemia is vital because it can rapidly progress to renal failure or fatal arrhythmias, making preservation of renal function through hydration the cornerstone of immediate management ^[3].

Why Other Options Are Not the Highest Priority
- Preparing for immediate hemodialysis (Option 2) is reserved for patients with refractory hyperkalemia, severe fluid overload unresponsive to diuretics, or symptomatic uremia. While dialysis is a definitive rescue therapy, it is not the first-line nursing priority when the patient first develops TLS; initial management focuses on aggressive hydration and pharmacologic measures to prevent the need for dialysis.
- Administering calcium gluconate (Option 3) is indicated to stabilize the cardiac membrane in the presence of hyperkalemia-induced ECG changes or arrhythmias. However, hypocalcemia in TLS is typically secondary to hyperphosphatemia, and routine calcium administration without addressing the underlying hyperphosphatemia can increase the risk of calcium-phosphate precipitation in tissues. It is not the primary preventive or initial intervention.
- Giving allopurinol (Option 4) reduces uric acid production by inhibiting xanthine oxidase, but it does not degrade existing uric acid and takes time to lower serum levels. A real-world study comparing anti-hyperuricemic therapies in hematologic malignancies found that rasburicase (which rapidly breaks down existing uric acid) may be associated with differences in TLS-related mortality, but allopurinol alone is insufficient as the sole immediate intervention once TLS is established . Hydration remains the foundational step, often initiated concurrently with hypouricemic agents.

Clinical Application and Monitoring
For a patient developing TLS after rituximab, the nurse should initiate IV normal saline at rates typically ranging from 200 to 250 mL/hour, with the goal of maintaining urine output at or above 2 mL/kg/hour. Strict intake and output monitoring, daily weights, and frequent assessment of serum electrolytes (potassium, calcium, phosphate), uric acid, and creatinine are essential. Cardiac monitoring is critical to detect early signs of hyperkalemia, such as peaked T-waves or widened QRS complexes ^[3]. The case report on bendamustine-rituximab reinforces that individualized prophylaxis, patient education about symptoms, and close monitoring during the early cycles of therapy are essential to prevent progression to multiorgan failure ^[1].