Thrombocytosis

Differential Diagnosis

• Primary
  • Essential thrombocythemia
  • Polycythemia vera
• Secondary
  • Transient process
    • Acute blood loss
    • Rebound from thrombocytopenia
    • Acute phase reactant in acute infection or inflammatory processes
    • Response to exercise
  • Sustained process
    • Iron deficiency (most common reason for referral to hematologist)
    • Hemolytic anemia
    • Asplenia
    • Cancer
    • Chronic inflammatory or infectious diseases
      • Connective-tissue disorders
      • Temporal arteritis
      • Inflammatory bowel disease
      • Tuberculosis
      • Chronic pneumonitis
    • Drug reactions
      • Vincristine
      • All-trans-retinoic acid
      • Cytokines
      • Growth factors

Clinical Manifestations

• Primary/clonal more likely if:
  • Digital ischemia
  • Cerebrovascular ischemia
  • Large-vessel thrombosis
  • Bleeding
  • Splenomegaly
  • Giant platelets

Investigations

• Labs
  • CBC
  • Peripheral film, for platelet size
  • ESR/CRP, rule out underlying inflammatory disorder
• Other