Thrombocytosis
- Increase in platelet count
- Platelet count greater than 450,000/uL
- Primary: Myeloproliferative disorder (e.g., essential thrombocythemia)
- Secondary: Reactive to inflammation, infection, blood loss, or malignancy
Thrombocytopenia
- Decrease in platelet count
- Platelet count less than 150,000/uL
- Primary: Immune thrombocytopenia (ITP), aplastic anemia
- Secondary: Medications (e.g., heparin, antiplatelet drugs), infections, bone marrow failure, pregnancy
Key Differences
| Feature | Thrombocytosis | Thrombocytopenia |
|---|---|---|
| Platelet count | >450,000/uL | <150,000/uL |
| Primary cause | Myeloproliferative disorder | Idiopathic, autoimmunity, bone marrow failure |
| Secondary causes | Inflammation, infection, blood loss | Medications, infections, pregnancy |
| Associated symptoms | Thrombosis, bleeding (less common) | Bleeding, bruising, fatigue |
| Treatment | Plateletpheresis, cytoreductive therapy | Transfusions, corticosteroids, immunosuppressants |