What is the treatment for thrombocytosis (increased platelets)?

Treatment for Thrombocytosis (Increased Platelets)

The treatment for thrombocytosis depends on its cause, with cytoreductive therapy indicated for high-risk patients with myeloproliferative neoplasms, while low-dose aspirin is recommended for all patients with essential thrombocythemia to prevent thrombotic complications. 1, 2

Diagnostic Approach

• Determine if thrombocytosis is:

  • Primary (clonal): Associated with myeloproliferative neoplasms
  • Secondary (reactive): Due to infection, inflammation, iron deficiency, or other causes

• Key diagnostic tests:

  • Complete blood count with peripheral smear
  • JAK2, CALR, and MPL mutation testing
  • Bone marrow examination (if primary thrombocytosis suspected)
  • Inflammatory markers (to identify reactive causes)

Treatment Algorithm

1. Secondary/Reactive Thrombocytosis

• Treat the underlying cause (infection, inflammation, iron deficiency)
• Usually no specific treatment for the elevated platelet count is required
• Platelet count typically normalizes once underlying condition resolves

2. Primary Thrombocytosis (Essential Thrombocythemia)

Risk Stratification:

• Very low risk: Age ≤60 years, no thrombosis history, JAK2 wild-type
• Low risk: Age ≤60 years, no thrombosis history, JAK2 mutation present
• Intermediate risk: Age >60 years, no thrombosis history, JAK2 mutation present
• High risk: Thrombosis history or age >60 years with JAK2 mutation 2

Treatment Based on Risk:

• Very low/Low risk:

  • Low-dose aspirin (81-100 mg daily)
  • Consider twice daily aspirin for low-risk disease 2
  • Monitor for bleeding complications

• Intermediate risk:

  • Low-dose aspirin
  • Consider cytoreductive therapy on an individual basis 1

• High risk:

  • Low-dose aspirin
  • Cytoreductive therapy with one of the following:
    • Hydroxyurea (first-line): Starting dose 15-20 mg/kg/day 1
    • Interferon-α (first-line, especially in younger patients) 1
    • Anagrelide (second-line): Starting dose 0.5 mg four times daily or 1 mg twice daily 3
    • Busulfan (second-line, typically for older patients) 1, 2

Special Considerations:

• Extreme thrombocytosis (>1,000 × 10⁹/L):

  • Higher risk of bleeding complications
  • Cytoreductive therapy should be considered even in otherwise low-risk patients 1
  • Target platelet count <600 × 10⁹/L

• Anagrelide dosing:

  • Starting dose: 0.5 mg four times daily or 1 mg twice daily
  • Maintain starting dose for at least one week
  • Titrate to maintain target platelet counts
  • Maximum dose: 10 mg/day (not exceeding 2.5 mg in a single dose) 3
  • Reduce dose in moderate hepatic impairment (start with 0.5 mg/day) 3

Monitoring

• Regular platelet count monitoring
• Assess for thrombotic or hemorrhagic complications
• Monitor for medication side effects:
  • Hydroxyurea: Cytopenias, mucocutaneous ulceration
  • Anagrelide: Cardiovascular effects (palpitations, tachycardia), headache
  • Interferon-α: Flu-like symptoms, depression

Treatment Endpoints

• Target platelet count <400-450 × 10⁹/L
• Resolution of symptoms (headaches, lightheadedness, acral paresthesias)
• Prevention of thrombotic and hemorrhagic complications

Cautions

• Aspirin should be withdrawn in case of major bleeding 1
• Monitor for cardiovascular toxicity with anagrelide (QT prolongation and ventricular tachycardia reported) 3
• Patients receiving multiple cytotoxic agents have a higher risk of developing acute myeloid leukemia/myelodysplastic syndromes 1

The treatment approach should focus on preventing thrombotic complications while minimizing bleeding risk, with cytoreductive therapy reserved for high-risk patients or those with extreme thrombocytosis.