What is the role of bicarbonate in Tumor Lysis Syndrome (TLS)?

From the Guidelines

Bicarbonate administration is not routinely recommended in tumor lysis syndrome (TLS) unless severe metabolic acidosis is present. In TLS, rapid breakdown of cancer cells releases intracellular contents including potassium, phosphate, and nucleic acids that metabolize to uric acid, leading to electrolyte abnormalities and potential kidney injury. While alkalinization of urine with sodium bicarbonate was historically used to increase uric acid solubility, this practice is no longer standard care since the introduction of rasburicase and allopurinol 1. Bicarbonate therapy can worsen hypocalcemia by increasing calcium-phosphate precipitation and may contribute to volume overload. If bicarbonate is needed for severe acidosis (pH < 7.2), it should be administered cautiously at 50-100 mEq in 1L of hypotonic solution, infused at 150-200 mL/hour while monitoring electrolytes, especially calcium.

The primary management of TLS focuses on:

• Aggressive hydration (2-3 L/m²/day)
• Allopurinol (100-300 mg orally every 8 hours or 200-400 mg/m²/day divided)
• Rasburicase (0.1-0.2 mg/kg as a single dose) for hyperuricemia Along with careful electrolyte monitoring and correction, addressing the underlying metabolic derangements directly rather than relying on bicarbonate therapy provides more effective management of TLS 1.

Key considerations in TLS management include:

• Hydration should start at least 48 hours before tumor-specific therapy
• Urine output should be kept at least 100 mL/hour in adults (3 mL/kg/hour in children <10 kg body weight)
• Loop diuretics may be required to maintain urine output, except for patients with concomitant obstructive uropathy or hypovolemia
• Unless other clinical conditions require urine alkalinization, urines should not be alkalinized in patients who receive concomitant rasburicase therapy 1.

From the Research

Tumor Lysis Syndrome and Bicarbonat

• Tumor lysis syndrome (TLS) is an oncological emergency characterized by a classic tetrad of hyperuricemia, hyperkalemia, hyperphosphatemia, and hypocalcemia 2.
• The management of TLS consists of aggressive intravenous hydration, diuretic therapy, urinary alkalization, and inhibition of urate production by high-dose allopurinol 3.
• Bicarbonat is mentioned as a treatment option for hyperkalemia, along with sodium polystyrene sulfonate, hypertonic glucose and insulin, and loop diuretics 3.

Role of Bicarbonat in TLS Management

• There is limited information on the specific role of bicarbonat in TLS management, but it is mentioned as a treatment option for hyperkalemia 3.
• The primary focus of TLS management is on aggressive hydration, electrolyte management, and the use of hypouricemic agents 2.
• Other treatment options for hyperphosphatemia and hypocalcemia include phosphate binders and continuous intravenous infusion of calcium gluconate 3.

Comparison with Other Treatment Options

• Rasburicase, a recombinant urate oxidase, has been shown to be effective and well tolerated in the prevention and treatment of chemotherapy-induced hyperuricemia 3, 4, 5.
• Allopurinol and rasburicase are also used in the management of TLS, with rasburicase offering a more rapid reduction in serum uric acid levels 4, 5.
• The choice of treatment option may depend on the individual patient's risk factors and clinical presentation 6.