Thrombocythaemia
Essential thrombocythaemia is a high-platelet disorder. (The paper prints "thrombocytopenia", which is a typing error.)
What our notes say
- Essential thrombocythaemia is a high-platelet disorder. (The paper prints "thrombocytopenia", which is a typing error.) (Internal Medicine (MBIM 4100) main exam, Paper One: 3 July 2019)
- Thrombocytosis — reactive (infection, inflammation, iron deficiency, post-splenectomy) vs primary/clonal (essential thrombocythaemia) (Year 3: Haematology and Blood Transfusion Pathology)
- | Essential thrombocythaemia (ET) | Megakaryocytic | JAK2 (most common), CALR, MPL (★) | (Acute Leukaemia (AML/ALL) & WBC Disorders: Hematology Guide)
- | Primary (Essential Thrombocythaemia) | Myeloproliferative disorder | Impaired — high numbers, poor function; may paradoxically bleed OR clot | (Platelet Disorders)
- Essential thrombocythaemia — highest platelet count of all MPDs; can exceed 1 million (Platelet Disorders)
Practice questions on Thrombocythaemia
Essential thrombocythaemia presenting with platelet count >1000×10⁹/L paradoxically causes
- Only thrombosis
- Only bleeding
- Both thrombosis and bleeding
- Neither, as it is asymptomatic always
Answer: C. Very high platelet counts consume vWF large multimers (acquired vWD), causing bleeding, while platelet activation causes thrombosis simultaneously. ---
Which cytokine mutation is most commonly associated with essential thrombocythaemia?
- BCR-ABL
- CALR
- MPL
- JAK2
Answer: D. JAK2 V617F is the most common driver mutation in essential thrombocythaemia, found in roughly half of cases. ---