From the Guidelines
Thrombocytosis is primarily caused by myeloproliferative disorders, such as polycythemia vera (PV) and essential thrombocythemia (ET).
Key Factors Contributing to Thrombocytosis
- Genetic mutations: The presence of certain genetic mutations, such as the PIA2 allele of platelet glycoprotein (GP) IIIa, can increase the risk of arterial thrombosis in patients with PV 1.
- Abnormal platelet function: Qualitative platelet defects, including diminished response to prostaglandin D2 and increased production of thromboxane A2, can contribute to thrombocytosis 1.
- Pro-thrombotic state: A baseline pro-thrombotic state in PV, characterized by reduced levels of physiologic anticoagulants and decreased fibrinolytic activity, can also contribute to thrombocytosis 1.
Clinical Implications
Thrombocytosis can lead to an increased risk of thrombotic events, such as arterial thrombosis and microvascular disturbances, including erythromelalgia 1. Additionally, some patients with PV may experience bleeding diathesis due to acquired von Willebrand disease, which is associated with extreme thrombocytosis and abnormal platelet function 1.
From the Research
Causes of Thrombocytosis
Thrombocytosis can be classified as primary or secondary. Primary thrombocytosis is a rare clonal disease, often associated with myeloproliferative disorders such as essential thrombocythemia, polycythemia vera, and primary myelofibrosis 2, 3, 4, 5. Secondary or reactive thrombocytosis is more common and can be caused by various factors, including:
- Infection 6, 5
- Chronic inflammation 6, 5
- Iron deficiency 2, 5
- Tissue damage 5
- Cancer 2
- Drugs 2
- Surgical or functional splenectomy 2
Classification of Thrombocytosis
Thrombocytosis can be classified based on the platelet count:
- Mild: >500,000 μL and <700,000 μL 2
- Moderate: >700,000/μL and <900,000/μL 2
- Severe: >900,000/μL 2
- Extreme: >1,000/μL 2
Diagnostic Approach
Diagnosing the cause of thrombocytosis requires a multifaceted approach, including: