trombocytosis

Trombocytosis refers to an elevated platelet count in the blood, typically defined as a platelet level exceeding 450,000 per microliter (µL) in adults, though thresholds may vary slightly depending on laboratory standards and clinical context. Platelets, or thrombocytes, are essential for blood clotting and wound healing, playing a key role in hemostasis. While mild increases in platelet count are often asymptomatic, severe thrombocytosis can pose risks such as an increased likelihood of thrombosis (blood clot formation) or hemorrhage due to platelet dysfunction.

The condition may arise from primary or secondary causes. Primary thrombocytosis, also known as essential thrombocythemia, is a rare myeloproliferative disorder where the bone marrow produces an excessive number of platelets independently of external stimuli. Secondary thrombocytosis is more common and often stems from underlying conditions such as chronic inflammation, infection, iron deficiency, malignancy, or the removal of the spleen (splenectomy). Certain medications, such as corticosteroids or cytokines like interleukin-6, may also trigger a reactive increase in platelet production.

Diagnosis involves a thorough medical history, physical examination, and laboratory testing, including a complete blood count (CBC) to confirm elevated platelet levels. Further evaluation may include bone marrow biopsy to rule out primary disorders, assessment of inflammatory markers, and investigation of potential secondary causes. Symptoms, if present, may include fatigue, headache, blurred vision, or signs of thrombosis, though many individuals remain asymptomatic.

Management depends on the underlying cause. For secondary thrombocytosis, addressing the root condition—such as treating an infection or correcting iron deficiency—often resolves the elevated platelet count. In cases of primary thrombocytosis, particularly when associated with high-risk features like advanced age or prior thrombosis, cytoreductive therapy with medications such as hydroxyurea or interferon may be recommended to reduce platelet counts and mitigate complications. Regular monitoring is essential to manage symptoms and prevent thrombotic events.