Critical Care Medicine-Hematologic and Oncologic Disorders>>>>>White Blood Cell Disorders
Question 3#

A 62-year-old male is admitted with fatigue and new-onset shortness of breath. His white blood count is 85,000/µL and bone marrow biopsy shows 35% myeloblasts. He is started on induction chemotherapy for acute myeloid leukemia. During treatment, his creatinine rises and he develops hyperuricemia.

Which of the following statements is FALSE regarding his management?

A. He should receive hydration with intravenous fluids with a target urine output of at least 2 mL/kg/h
B. He should have continuous cardiac monitoring and measurement of electrolytes, creatinine, and uric acid every 4 to 6 hours
C. Rasburicase is contraindicated if he has a glucose-6-phosphate dehydrogenase deficiency
D. His uric acid level will decrease rapidly after starting allopurinol

Correct Answer is D


Correct Answer: D

Tumor lysis syndrome arises from massive tumor cell death. Cell lysis results in release of potassium, phosphorus, and nucleic acids causing metabolic derangements including hyperuricemia, hyperkalemia, hypocalcemia, and hyperphosphatemia. Diagnostic criteria for tumor lysis syndrome include having two or more of these abnormalities occurring within 3 days before or up to 7 days after initiation of cancer therapy. Tumor lysis syndrome is an oncologic emergency, and treatment must begin immediately as complications including renal failure, seizures, cardiac arrhythmias, and death may ensue. Continuous cardiac monitoring should be started along with frequent measurement of electrolytes, creatinine, and uric acid.

Treatment includes intravenous hydration with a target urine output of at least 2 mL/kg/h. Diuretics may be given if enough fluid has been administered and target urine output has not been reached. Hyperkalemia may be treated with oral sodium polystyrene sulfonate though hemodialysis may be needed with severe hyperkalemia, especially in the setting of acute kidney injury. Hyperphosphatemia may be treated with phosphate binders. 

Allopurinol and rasburicase both reduce the level of uric acid. Allopurinol blocks the xanthine oxidase enzyme and prevents the formation of uric acid. However, the uric acid level may take several days to decrease because any existing uric acid must still be excreted. Rasburicase breaks down uric acid to allantoin which is easily excreted renally and can reduce uric acid levels within hours. It is contraindicated in patients with glucose-6-phosphate dehydrogenase deficiency because of a high risk of hemolysis and methemoglobinemia. 

References :

  1. Howard SC, Jones DP, Pui CH. The tumor lysis syndrome. N Engl J Med. 2011;364:1844-1854.
  2. Mirrakhimov AE, Voore P, Khan M, Ali AM. Tumor lysis syndrome: a clinical review. World J Crit Care Med. 2015;4:130-138.