What is the treatment approach for thrombocytosis (elevated platelet count)?

Treatment Approach for Thrombocytosis (Elevated Platelet Count)

The treatment of thrombocytosis should be directed at the underlying cause, with anagrelide being the primary pharmacologic treatment for thrombocythemia secondary to myeloproliferative neoplasms to reduce elevated platelet counts and the risk of thrombosis. 1

Diagnostic Approach

• First determine if thrombocytosis is primary (myeloproliferative neoplasm) or secondary (reactive) as this fundamentally changes management 2
• Secondary causes include tissue injury (32.2%), infection (17.1%), chronic inflammatory disorders (11.7%), and iron deficiency anemia (11.1%) 2
• Primary thrombocytosis is associated with higher median platelet counts and greater incidence of thrombosis compared to secondary thrombocytosis 2

Treatment of Secondary Thrombocytosis

• Treat the underlying condition (infection, inflammation, iron deficiency) 2
• Reactive thrombocytosis, even with platelet counts >1000 × 10⁹/L, has not been shown to cause thrombosis or bleeding due to acquired von Willebrand factor defects 3
• No specific antiplatelet therapy is typically required for reactive thrombocytosis 3

Treatment of Primary Thrombocytosis (Essential Thrombocythemia)

Risk Stratification

• High-risk patients: Age ≥60 years or history of thrombosis at any age 4
• Intermediate-risk patients: Age <60 years with platelet counts >1,500 × 10⁹/L or significant cardiovascular risk factors 4
• Low-risk patients: Age <60 years, no history of thrombosis, no cardiovascular risk factors, platelet counts <1,500 × 10⁹/L 4

Pharmacologic Management

• High-risk patients:

  • Anagrelide is indicated to reduce elevated platelet count and risk of thrombosis 1
  • Starting dose for adults is 0.5 mg four times daily or 1 mg twice daily 1
  • Starting dose for pediatric patients is 0.5 mg per day 1
  • Maintain starting dose for at least one week before titrating to target platelet counts 1
  • Maximum dose increment of 0.5 mg/day in any one week; do not exceed 10 mg/day or 2.5 mg in a single dose 1
  • Alternative options include hydroxyurea or interferon-alpha 4

• Intermediate-risk patients:

  • Can be observed or treated with anagrelide, hydroxyurea, or interferon-alpha 4
  • Treat cardiovascular risk factors 4

• Low-risk patients:

  • Can be observed or placed on low-dose aspirin 4

Aspirin Therapy

• Low-dose aspirin (81-100 mg) once daily is recommended for all essential thrombocythemia risk categories except very low-risk patients 5
• Twice daily aspirin administration may be more effective than once daily dosing in patients with high platelet counts 5
• Plain aspirin should be preferred over enteric-coated aspirin due to potential resistance to the latter in essential thrombocythemia patients 5
• Avoid aspirin in patients with platelet counts >1,500 × 10⁹/L due to bleeding risk 4, 6

Special Considerations

• Cardiovascular toxicity: Obtain pre-treatment cardiovascular examination including ECG before starting anagrelide due to risk of QT prolongation and ventricular tachycardia 1
• Pulmonary hypertension: Assess underlying cardiopulmonary disease prior to initiating anagrelide therapy 1
• Bleeding risk: Monitor patients for bleeding, especially those receiving concomitant therapy with other drugs known to cause bleeding 1
• Moderate hepatic impairment: Start anagrelide at 0.5 mg per day 1

Monitoring and Follow-up

• Regular monitoring of platelet counts during treatment 1
• Assess for bleeding risk factors including concurrent coagulopathy, liver or renal impairment, and infection 7
• Consider referral to hematology if platelet count drops below 50 × 10³/μL or continues to decline despite management 8