What is the initial workup and management for a patient with thrombocytosis?

From the Guidelines

The initial workup for thrombocytosis should begin with a complete blood count with differential, peripheral blood smear, and basic metabolic panel to distinguish between primary (clonal) and secondary (reactive) causes, as recommended by recent guidelines 1. The workup should include additional testing such as iron studies, inflammatory markers (ESR, CRP), JAK2 V617F mutation analysis, and possibly bone marrow biopsy if primary thrombocytosis is suspected. Management depends on the underlying cause, with secondary thrombocytosis treatment focusing on addressing the underlying condition (infection, inflammation, iron deficiency, etc.). For primary thrombocytosis, particularly essential thrombocythemia, risk stratification guides therapy, with high-risk patients (age >60, prior thrombosis, platelet count >1,500,000/μL) receiving cytoreductive therapy with hydroxyurea (starting at 500-1000 mg daily, adjusted to maintain platelets <400,000/μL) plus low-dose aspirin (81-100 mg daily) 1. Low-risk patients may be managed with aspirin alone, and in emergency situations with extreme thrombocytosis and symptoms, plateletpheresis may be considered. Regular monitoring of blood counts is essential, with frequency determined by disease stability and treatment regimen, as outlined in recent clinical practice guidelines 1. Key considerations in management include:

• Addressing cardiovascular risk factors, such as smoking, diet, exercise, thrombotic and hemorrhagic risk factors 1
• Considering antifibrinolytic agents for bleeding that is refractory to transfusions, and iron chelation for patients with high transfusion burden 1
• Providing counseling on reducing cardiovascular risk factors and managing hyperuricemia with allopurinol or rasburicase 1 This approach helps prevent thrombotic and hemorrhagic complications while addressing the underlying pathophysiology of abnormal platelet production or destruction.

From the Research

Initial Workup for Thrombocytosis

The initial workup for a patient with thrombocytosis involves a thorough evaluation to distinguish between primary (essential) thrombocytosis and secondary (reactive) thrombocytosis. The following steps are recommended:

• Obtain a complete blood count (CBC) to confirm the elevated platelet count [ 2 ]
• Perform a physical examination to look for signs of inflammation, infection, or malignancy [ 3 ]
• Obtain a detailed medical history, including questions about recent infections, surgeries, or medications [ 3 ]
• Order laboratory tests, such as:
  • Erythrocyte sedimentation rate (ESR) [ 4 ]
  • C-reactive protein (CRP) [ 4 ]
  • Ferritin [ 4 ]
  • Lactate dehydrogenase (LDH) [ 4 ]
• Consider testing for myeloid mutations, such as JAK2, CALR, and MPL, to help differentiate between essential thrombocythemia and secondary thrombocytosis [ 3 ]

Differential Diagnosis

The differential diagnosis for thrombocytosis includes:

• Essential thrombocythemia (ET) [ 2 ]
• Secondary (reactive) thrombocytosis due to:
  • Inflammation or infection [ 4 ]
  • Iron deficiency anemia [ 5 ]
  • Malignancy [ 4 ]
  • Chronic myeloproliferative disease (CMPD) [ 5 ]
• Other rare causes, such as celiac disease [ 5 ]

Management

The management of thrombocytosis depends on the underlying cause. For essential thrombocythemia, treatment aims to reduce the risk of thrombotic complications by addressing cardiovascular risk factors and using antiplatelet agents and cytoreductive therapy [ 2 ]. For secondary thrombocytosis, treatment focuses on addressing the underlying cause, such as iron deficiency anemia or inflammation [ 5 ].