Board Questions

1. Which of the following is the least common manifestation of leukostasis? 

a) Acute Kidney Injury
b) Respiratory Distress
c) Neurological impairment
d) Fever

2. You have a 6 yo F who comes in with several days history of fever, easy bruising, pallor, and fatigue. CBC reveals a WBC of 180K with 90% blasts, Hgb of 6.5, and Platelets of 70. She is tachypneic to a respiratory rate of 40, has had diminished urine output, and demonstrates some confusion and listlessness. Which of the following would generally be contraindicated in her acute management?

a) Steroids
b) Hydroxyurea
c) Fluid boluses
d) pRBC transfusions

3. You have a 2 yo patient who comes in with new onset AML. She has a moderate oxygen requirement (3L NC) and appears lethargic. A diagnosis of leukostasis is made. There is no evidence of tumor lysis and the decision is made to proceed with leukapheresis. Post-leukapheresis, her CBC reveals a WBC of 35K (from 150K pre-luekapheresis), Hgb 8.5, and platelets of 19K. Her oxygen requirement is stable and her respiratory distress appears somewhat improved. She is also more alert and responsive. Tumor lysis labs reveal a K of 4.7 and a uric acid of 4.5 mg/dl. Which one of the following therapies is indicated?

a) Rasburicase
b) Allopurinol
c) Calcium Chloride
d) Platelet Transfusion



ANSWERS & EXPLANATIONS

1. A- Kidney Injury. Fever, respiratory distress, and neurological impairment are all very common manifestations of leukostasis.

2. D- This patient likely has leukemia with evidence of leukostasis (respiratory and neurological manifestations). Given her already increased blood viscosity due to circulating blasts, pRBC transfusion is generally contraindicated as it can exacerbate leukostasis leading to further capillary plugging, localized ischemia, and worsening respiratory/neurological status. Steroids, hydroxyurea, and fluid may all be indicated (although decisions regarding induction chemotherapy and hydroxyurea should obviously be made in close consultation with hematology/oncology.

3. D- The risk of intracranial hemorrhage following leukapheresis is greatest after the WBC count has been greatly reduced (perhaps indicating risk of reperfusion injury). Hence, while it may appear counterintuitive to transfuse platelets when concerned about capillary plugging and viscosity, platelets are generally indicated to keep platelet counts >20-30K to mitigate the risk of intracranial hemorrhage. Rasburicase is a recombinant form of urate oxidase used to break down uric acid. Give her level of 4.5 mg/dl, rasburicase is not indicated at this time (generally given when above 8 mg/dL), although one should continue to monitor the uric acid level with frequent tumor lysis labs. Similarly, allopurinol is a xanthine oxidase inhibitor used to prevent purine (A & G) breakdown into uric acid. Its use has decreased dramatically after the introduction of rasburicase therapy and would not be indicated (perhaps unless there was significant difficulty controlling uric acid levels despite the use of rasburicase-which would be rather rare. Calcium chloride might be used to treat hyperkalemia but given the K of 4.7, would not be indicated in this patient. 

Comments