A 47-year-old female with newly diagnosed acute myeloid leukaemia presents with the following blood results:
|
Parameter |
Patient Value |
Adult Normal Range |
|
Haemoglobin |
89 g/L* |
120 – 160 |
|
White Cell Count |
110.0 x 109/L* |
4.0 – 11.0 |
|
Platelet count |
32 x 109/L* |
150 – 350 |
|
Blast cells |
104 x 109/L |
a) What specific issues might you anticipate as a result of the white cell count, and what clinical problems might these cause?
What management strategies would you employ to prevent or treat these issues? (60% marks)
1. Leukostasis/Hyperviscosity syndrome: white cell plugs in the microvasculature.
Most commonly affects lungs (dyspnoea, hypoxia, CXR infiltrates) and brain (visual changes, headache, dizziness, tinnitus, confusion progressing to coma)
Can also affect Heart (ischaemia, failure), kidney (AKI), liver/bowel ischaemia.
2. Tumour lysis syndrome- either spontaneous or in response to chemotherapy
Electrolyte abnormalities including hyperkalaemia, hyperphosphataemia and hypocalcaemia. Can cause arrhythmias, seizures and sudden death.
3. Artifactually low PaO2 on ABG due to metabolically active blasts which continue to utilise O2 in the test tube (SpO2 more reliable)
Management:
Keep hydrated
Start allopurinol or rasburicase to prevent TLS
Monitor FBC. Avoid RBC transfusion if possible (increases viscosity)
If there is a delay or contraindication to starting chemotherapy immediately, consider leukapheresis if symptomatic of hyper-viscosity.
For ABGs – sample transported on ice, analyse immediately. Monitor SpO2.
Examiners Comments:
When asked for a specific number of responses (e.g. 'three causes of') please supply this number of responses. Extra responses will not gain extra marks. If there are more causes, then list the most likely. Many candidates did not appear to pay attention to the mark allocation and gave insufficient detail in sections of the question worth the most marks.
As a table, this answer makes more sense:
| specific issues might you anticipate | Leukostasis | Tumour lysis syndrome |
| What clinical problems might these cause? |
|
|
| Management |
|
|
Strictly speaking, this patient has hyperleukocytosis rather than leukostasis. Ganzel et al (2012) define it as any WCC in excess of 100,000, admitting that this is a fairly arbitrary cut-off. Leukostasis per se is a clinical manifestation of hyperleukocytosis, characterised by vascular occlusion and tissue hypoxia. It is seen with high WCCs, but usually quite a lot higher than this one (usually 400,000-1,000,000).
One last interesting feature is the need to refrigerate the ABGs. An excess of highly metabolically active blasts in the blood sample gives rise to "leukocyte larceny", where the hungry cells metabolise all the gases while you wait for the ABG machine to self-calibrate. The result is a spurious hypoxia and hypoglycaemia.
Porcu, Pierluigi, et al. "Hyperleukocytic leukemias and leukostasis: a review of pathophysiology, clinical presentation and management." Leukemia & lymphoma 39.1-2 (2000): 1-18.
Ganzel, Chezi, et al. "Hyperleukocytosis, leukostasis and leukapheresis: practice management." Blood reviews 26.3 (2012): 117-122.
Tiu, Ramon V., et al. "Tumor lysis syndrome." Seminars in thrombosis and hemostasis. Vol. 33. No. 4. New York: Stratton Intercontinental Medical Book Corporation, c1974-, 2007.
Howard, Scott C., Deborah P. Jones, and Ching-Hon Pui. "The tumor lysis syndrome." New England Journal of Medicine 364.19 (2011): 1844-1854.
Cairo, Mitchell S., and Michael Bishop. "Tumour lysis syndrome: new therapeutic strategies and classification." British journal of haematology 127.1 (2004): 3-11.
Gartrell, Kevin, and W. Rosenstrauch. "Hypoxaemia in patients with hyperleukocytosis: true or spurious, and clinical implications." Leukemia research 17.11 (1993): 915-919.