From the Guidelines
Thrombocytosis, or a high platelet count, can be caused by primary factors such as myeloproliferative neoplasms, including essential thrombocythemia, or secondary factors like infections, inflammation, iron deficiency anemia, and certain medications, with the most recent evidence suggesting that myeloproliferative neoplasms are a common underlying cause of thrombocytosis 1.
Primary Causes of Thrombocytosis
- Myeloproliferative neoplasms, such as essential thrombocythemia, are characterized by the overproduction of platelets due to genetic mutations in blood-forming cells 1.
- The presence of the JAK2V617F mutation is a common feature of myeloproliferative neoplasms and is associated with an increased risk of thrombosis 1.
Secondary Causes of Thrombocytosis
- Infections, inflammation, and iron deficiency anemia can all lead to an increase in platelet production as a reactive response 1.
- Certain medications, such as epinephrine, vincristine, and all-trans retinoic acid, can also increase platelet counts 1.
- Hormonal factors, including pregnancy and the use of birth control pills, can temporarily elevate platelet counts 1.
Diagnosis and Management
- It is essential to determine whether the cause of thrombocytosis is primary or secondary, as treatment approaches differ 1.
- Primary thrombocytosis may require medications like hydroxyurea or anagrelide to reduce platelet production, while secondary thrombocytosis is managed by treating the underlying condition 1.
- Platelet counts typically return to normal once the underlying issue is resolved 1.
From the Research
Causes of Thrombocytosis
Thrombocytosis, defined as a platelet count above 450×10^9/L, can occur as a primary event accompanying hematological diseases or as a secondary event 2. The causes of thrombocytosis can be categorized into:
- Primary thrombocytosis: caused by myeloproliferative neoplasms (MPNs) such as essential thrombocythemia (ET) 3, 2, 4
- Secondary thrombocytosis: caused by various conditions such as:
Diagnostic Approach
The diagnostic approach to thrombocytosis involves excluding spurious thrombocytosis and determining the underlying cause of the elevated platelet count 4. This may involve testing for molecular markers indicative of MPNs, such as driver-gene mutations 2.
Clinical Characteristics
Patients with primary thrombocytosis tend to have higher platelet counts and a higher incidence of thrombosis compared to those with secondary thrombocytosis 2. The clinical characteristics of thrombocytosis may also include splenomegaly and qualitative platelet abnormalities 6.