Critical Care Medicine-Hematologic and Oncologic Disorders>>>>>Oncological Syndromes
Question 1#

A 19-year-old man with acute lymphoblastic leukemia is found to be lethargic and complains of nausea and muscle cramps after receiving cytotoxic therapy. A basic metabolic panel is notable for:

An ECG is notable for peaked T waves and frequent premature ventricular complexes.

Which one of the following treatment options is MOST appropriate at this time?

A. Rasburicase
B. Allopurinol
C. Hemodialysis
D. IV fluid therapy

Correct Answer is C

Comment:

Correct Answer: C

The patient has symptomatic hyperkalemia, evidence by peaked T waves and a plasma potassium level of 6.9 mEq/L, which is an indication for emergent dialysis.

Tumor lysis syndrome (TLS) is an oncologic emergency caused by release of large amounts of potassium, phosphate, and uric acid into the plasma in response to tumor cell lysis resulting from cytotoxic therapy, radiation therapy, immunotherapy, or glucocorticoid therapy. Patients with highgrade lymphomas (Burkitt lymphoma) or acute lymphoblastic leukemia, those with large tumor burdens, or highly proliferative tumors are at higher risk for TLS. TLS can also occur spontaneously in highly proliferative tumors due to high cell turnover. 

Hyperuricemia leads to precipitation of uric acid crystals in the renal tubules and can cause acute kidney injury (AKI). Hyperphosphatemia and deposition of calcium phosphate crystals in the renal tubules can also lead to AKI. Hyperkalemia can lead to arrhythmias, including ventricular fibrillation and cardiac arrest.

The signs and symptoms of TLS occur from metabolic abnormalities (hyperkalemia, hyperphosphatemia, hyperuricemia) and associated development of AKI and include lethargy, nausea, vomiting, diarrhea, anorexia, muscle cramps, tetany, hematuria, arrhythmias, and cardiac arrest. 

Aggressive intravenous fluid therapy to increase renal perfusion and prevent precipitation of uric acid and calcium phosphate crystals in the renal tubules is the mainstay of TLS prophylaxis. Recommended urine output is 2 mL/kg/h. Rasburicase is the first-line hypouricemic agent for patients at high risk for TLS, especially those with renal or cardiac dysfunction, while allopurinol, a xanthine oxidase inhibitor which blocks the metabolism of hypoxanthine and xanthine to uric acid, is the first-line prophylactic agent in patients at intermediate risk for TLS. 

References:

  1. Thandra K, Salah Z, Chawla S. Oncological emergencies – The old, the new, the deadly. J Intensive Care Med. 2018; [Epub ahead of print].
  2. Coiffier B, Altman A, Pui CH, Younes A, Cairo MS. Guidelines for the management of pediatric and adult tumor lysis syndrome: an evidence-based review. J Clin Oncol. 2008;26:2767-2778.