Thrombocytosis

An abnormal increase in circulating platelet count (>450 × 10³/μL), associated with increased risk of thrombotic events due to excessive platelet-mediated clot formation.

Causes

• Primary (clonal myeloproliferative) thrombocytosis

  • Essential thrombocythemia

  • Polycythemia vera

  • Primary myelofibrosis

• Reactive (secondary) thrombocytosis

  • Acute or chronic infection/inflammation

  • Hemorrhage

  • Hemolytic anemia

  • Tissue injury: Surgery, burns, trauma

  • Splenectomy

• Malignancy

  • Lung cancer

  • Gastrointestinal cancer

  • Ovarian cancer

  • Other solid tumors

• Medications: Corticosteroids