Campbell and Green reported proposed criteria for primary thrombocythemia based on the patient's JAK2 mutation status. The authors are from the University of Cambridge.
Diagnosis of JAK2 positive primary thrombocythemia requires the presence of all 3 criteria.
Diagnosis of JAK2 negative primary thrombocythemia requires the presence of all 5 criteria.
Parameter
JAK2 Positive
JAK2 negative
platelet count per µL
> 450,000
> 600,000 on 2 occasions at least 1 month apart
JAK2 mutation
present
absent
other myeloid cancers or myelodysplasia
absent
absent
reactive cause for thrombocytosis
NA
absent
serum ferritin
NA
normal (> 20 µg/L)
where:
• Ferritin may show an acute phase reaction. I am not sure if this would impact the cutoff. Many of the causes of reactive thrombocytosis also cause an acute phase reaction, so this may be covered.
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