Tumor lysis syndrome (TLS)

• Topic review
  The full article, organized the way the exam asks it.
• ABIM-format MCQs
  Vignettes with an explanation for every wrong answer.
• Key facts
  The numbers and thresholds worth memorizing, up front.
• AI tutor
  MedBrain answers the question you're stuck on.

What this article covers

• Overview

  Tumor lysis syndrome (TLS) is a metabolic oncologic emergency caused by the release of tumor cell contents into the bloodstream, either spontaneously or as a result of treatment, producing…

• Epidemiology

  Occurs most commonly in acute leukemia and high-grade non-Hodgkin lymphoma, particularly Burkitt lymphoma, where the combination of large tumor burden and exquisite chemosensitivity produces rapid, massive cell death.

• Risk factors

  Large tumor burden and high proliferative rate, the dominant determinant of TLS risk, reflected in bulky disease, high white blood cell count, or elevated lactate dehydrogenase.

• Pathophysiology

  Rapid lysis of malignant cells, most often triggered by cytotoxic chemotherapy, releases a large intracellular potassium and phosphate load into the bloodstream, directly raising serum potassium and phosphate.

• Clinical features

  Gastrointestinal symptoms (nausea, vomiting, diarrhea, anorexia): often the earliest nonspecific symptoms, typically emerging within hours to a few days of starting chemotherapy in a high-risk patient.

• Differential diagnosis

  Cytokine release syndrome (after CAR T-cell therapy or other immunotherapy): fever, hypotension, and tachycardia with a temporal relationship to cellular immunotherapy rather than cytotoxic…

• Diagnosis

  TLS is confirmed by the laboratory pattern of hyperuricemia, hyperkalemia, hyperphosphatemia, and hypocalcemia arising in a patient with a large-burden, chemosensitive tumor around the time of…

• Management

  First, stratify risk and start prophylaxis before chemotherapy: intermediate-risk: IV hydration plus allopurinol 300 mg PO once daily, starting 1-2 days before chemotherapy, continued 3-7 days after or until values normalize.

• Complications

  Acute kidney injury, from uric acid and calcium-phosphate crystal precipitation in the renal tubules, the most common organ complication and often the trigger for renal replacement therapy.

• Prognosis

  Prompt recognition and risk-stratified prophylaxis prevent the great majority of clinically significant TLS, particularly in patients correctly identified as high risk before chemotherapy begins.

• Prevention

  Risk-stratify every patient before starting chemotherapy for a bulky, chemosensitive hematologic malignancy, and start prophylaxis before, not after, the first dose.