What is tumor lysis syndrome (TLS)?

• A. TLS is a form of cachexia caused by decreased appetite
• B. TLS is caused by massive tumor cell lysis with release of potassium, phosphate, and nucleic acids; catabolism leads to hyperuricemia; TLS most often occurs after the initiation of cytotoxic therapy
• C. TLS is a chronic metabolic condition due to renal failure
• D. TLS is a benign condition after transplantation

Answer: (B)

Tumor lysis syndrome occurs when a large number of tumor cells are destroyed rapidly, releasing their contents into the bloodstream. This sudden flood of intracellular potassium and phosphate, along with nucleic acids that are broken down into uric acid, leads to dangerous electrolyte changes—hyperkalemia, hyperphosphatemia, hyperuricemia, and secondary hypocalcemia from calcium phosphate precipitation. The high uric acid and phosphate can crystallize in the kidneys, causing acute kidney injury. TLS most often follows the initiation of cytotoxic therapy in patients with a high tumor burden or highly proliferative cancers, though it can occur spontaneously. Prevention and treatment focus on aggressive IV hydration to preserve kidney function, urate-lowering therapy (such as allopurinol or rasburicase), careful electrolyte management, and dialysis if needed for severe electrolyte or kidney dysfunction. It is not a form of cachexia, a chronic metabolic condition due to renal failure, or a benign post-transplant condition.