Increase in cell counts - thrombocytosis
Description
- Platelets >450 x10^9/L
- The whole task is one question: reactive or clonal?
| Reactive (~80-90%) | Clonal | |
|---|---|---|
| Platelet count | Usually <1000, but can exceed it | Any, often sustained >600 |
| Duration | Transient, tracks the trigger | Sustained over months |
| Spleen | Normal | Palpable in ~20-50% |
| Film | Normal platelet morphology | Giant/bizarre platelets, megakaryocyte fragments |
| Driver mutation | Absent | JAK2 / CALR / MPL |
| Thrombosis risk | Not increased | Increased |
| Ferritin/CRP | Often abnormal | Normal |
- *Extreme thrombocytosis (>1000) is more often reactive than clonal* - the number does not discriminate
- Spurious thrombocytosis: cryoglobulins, schistocytes, bacteria, leukaemic cell fragments counted as platelets
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