Essential Thrombocythemia: Diagnostic Criteria and Treatment
Statement (d) is correct: treatment consists of hydroxyurea and low-dose aspirin for high-risk patients with essential thrombocythemia. 1
Diagnostic Platelet Count Threshold
The provided answer options regarding diagnostic criteria are all incorrect based on current guidelines. The diagnosis of essential thrombocythemia requires sustained platelet elevation ≥450,000/mm³ according to WHO criteria, not the thresholds listed in options a, b, or c. 1 However, none of the answer choices accurately reflect this standard diagnostic criterion.
Treatment Approach for Essential Thrombocythemia
High-Risk Patients (Age ≥60 years and/or prior thrombosis)
The combination of hydroxyurea plus low-dose aspirin (81-100 mg daily) is the standard first-line treatment for high-risk essential thrombocythemia patients. 1
- Hydroxyurea has proven efficacy in preventing thrombotic complications in randomized controlled trials, reducing thrombotic events from 24% to 3.6% in high-risk patients. 2
- The target platelet count during treatment is <400 × 10⁹/L, not the diagnostic threshold. 1
- Low-dose aspirin (81-100 mg daily) is used concurrently for thrombosis prevention, not high-dose aspirin >1,000 mg as suggested in option (e). 1
Hydroxyurea Dosing and Monitoring
- Standard dosing is at least 2 g/day (or 2.5 g/day in patients >80 kg) for 3 months to assess response. 1, 3, 4
- Treatment resistance is defined as platelet count >600 × 10⁹/L after 3 months of adequate hydroxyurea dosing. 1, 3
- Monitor complete blood counts every 4-8 weeks once stabilized. 3
Critical Treatment Thresholds
Cytoreductive therapy is specifically indicated when:
- Platelet count >1,500 × 10⁹/L (due to increased bleeding risk, not thrombotic risk). 5, 6, 7
- Symptomatic or progressive splenomegaly develops. 1, 3
- Microvascular symptoms (erythromelalgia, transient neurological attacks) occur. 5
Common Pitfall to Avoid
High-dose aspirin (>1,000 mg) is never recommended in essential thrombocythemia. The standard dose is 81-100 mg daily. 1 High-dose aspirin increases bleeding risk without additional thrombotic protection, particularly problematic when platelet counts exceed 1,500 × 10⁹/L. 5, 7
Mandatory Discontinuation Criteria
Stop hydroxyurea immediately if any of the following occur:
- Absolute neutrophil count <1.0 × 10⁹/L 1, 3
- Platelet count <100 × 10⁹/L 1, 3
- Hemoglobin <10 g/dL 1, 3
- Development of leg ulcers or severe mucocutaneous manifestations 1, 3