The differential diagnosis for thrombocytosis can be broadly separated into primary/autonomous thrombocytosis (15%; myeloproliferative neoplasms eg ET, PV, MDS; familial thrombocytosis) and secondary/reactive thrombocytosis (85%). Causes of secondary thrombocytosis can be divided into transient and sustained processes. Amongst transient processes are acute blood loss, recovery from prior thrombocytopenia, acute infection/inflammation, and response to vigorous exercise. Sustained processes include Fe-deficiency, hemolytic anemia, asplenia, cancer, chronic inflammatory or infectious diseases (e.g., connective tissue disease, temporal arteritis, IBD, TB, chronic pneumonitis), and drug reactions (e.g., vincristine, ATRA, cytokines, growth factors). In this patient with ***, the most likely etiology is ***.
- assess for HA, CP, bleeding/clotting, visual disturbances
- assess for vasomotor symptoms (eg, erythromelalgia, flushing, pruritus), and constitutional symptoms
- CBC/diff, smear, ferritin, ESR/CRP
- heme referral for primary (urgent if symptomatic or >1M/uL) or reactive if worsening despite tx, thrombosis/hemorrhage, or symptomatic