From the Guidelines
Thrombocytosis workup should begin with a complete blood count with peripheral smear, inflammatory markers (ESR, CRP), iron studies, and JAK2 V617F mutation testing to determine if the thrombocytosis is reactive or primary. The initial evaluation is crucial in identifying the underlying cause of thrombocytosis, which can be either reactive (secondary) or primary. Reactive thrombocytosis is often caused by underlying conditions such as infection, inflammation, iron deficiency, malignancy, or recent surgery/trauma, and typically resolves when the underlying condition is treated 1.
Primary Thrombocytosis Evaluation
If reactive causes are ruled out, further evaluation for primary thrombocytosis, including myeloproliferative neoplasms like essential thrombocythemia, is necessary. This involves bone marrow biopsy and additional genetic testing (CALR, MPL mutations) to confirm the diagnosis. Risk stratification is essential for primary thrombocytosis, considering factors such as age >60, prior thrombotic events, cardiovascular risk factors, and platelet count >1,000/μL 1.
Management of Primary Thrombocytosis
High-risk patients typically require cytoreductive therapy, with hydroxyurea being the first-line treatment, starting at 500-1000 mg daily, plus low-dose aspirin (81-100 mg daily) 1. Anagrelide or rINFα are recommended as second-line therapy for essential thrombocythemia after hydroxyurea 1. Low-risk patients may only need aspirin, and the use of cytoreductive drugs in these patients is not generally indicated unless they have poorly controlled cardiovascular risk factors or a platelet count greater than 1,500 × 10^9/L, which increases the risk of bleeding 1.
Ongoing Management
Regular monitoring of platelet counts and adjustment of therapy based on response is necessary for optimal management of thrombocytosis. This approach helps in minimizing the risk of thrombotic and hemorrhagic complications associated with primary thrombocytosis. By prioritizing the most recent and highest quality evidence, the management strategy can be tailored to improve outcomes in terms of morbidity, mortality, and quality of life for patients with thrombocytosis 1.
From the FDA Drug Label
Anagrelide capsules are indicated for the treatment of patients with thrombocythemia, secondary to myeloproliferative neoplasms, to reduce the elevated platelet count and the risk of thrombosis and to ameliorate associated symptoms including thrombo-hemorrhagic events. Anagrelide is a platelet reducing agent indicated for the treatment of thrombocythemia, secondary to myeloproliferative neoplasms, to reduce the elevated platelet count and the risk of thrombosis and to ameliorate associated symptoms including thrombo-hemorrhagic events.
The further work up for thrombocytosis is not directly addressed in the provided drug labels.
- The labels discuss the treatment of thrombocythemia using anagrelide 2 2.
- They do not provide guidance on the initial evaluation or workup for thrombocytosis.
From the Research
Thrombocytosis Further Workup
Thrombocytosis is a condition characterized by an elevated platelet count, which can be either primary (essential thrombocythemia) or secondary (reactive thrombocytosis) 3. The initial step in evaluating thrombocytosis is to determine whether it is primary or secondary.
Differential Diagnosis
The differential diagnosis of thrombocytosis includes:
- Essential thrombocythemia (a myeloproliferative neoplasm) 4
- Reactive thrombocytosis (secondary to an underlying condition such as inflammation, infection, or iron deficiency) 3
- Other myeloproliferative disorders (such as polycythemia vera or chronic myeloid leukemia) 4
- Myelodysplastic syndromes associated with thrombocytosis 4
Diagnostic Evaluation
The diagnostic evaluation of thrombocytosis includes:
- Complete blood count (CBC) to confirm the elevated platelet count
- Blood smear to evaluate platelet morphology
- Bone marrow biopsy to assess bone marrow morphology and rule out other myeloproliferative disorders or myelodysplastic syndromes 4
- Molecular testing to detect mutations associated with essential thrombocythemia (such as JAK2, CALR, or MPL) 4
- Imaging studies to rule out underlying conditions that may be causing reactive thrombocytosis
Risk Stratification
Risk stratification is essential in patients with essential thrombocythemia to determine the risk of thrombotic events and guide treatment decisions 4. The risk factors include:
- Age > 60 years
- History of thrombosis
- Presence of JAK2 mutation
- Platelet count > 1000 x 10^9/L
Treatment
The treatment of essential thrombocythemia is aimed at preventing thrombotic events and reducing the risk of transformation to myelofibrosis or acute myeloid leukemia 4. The treatment options include: