What are the causes of thrombocytosis?

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Last updated: February 13, 2025 • View editorial policy

From the Guidelines

Thrombocytosis is primarily caused by myeloproliferative neoplasms (MPNs), such as polycythemia vera (PV) and essential thrombocythemia (ET) 1, 2, 3.

Common Causes of Thrombocytosis

  • Myeloproliferative neoplasms (MPNs): MPNs, including PV and ET, are characterized by the overproduction of platelets, leading to thrombocytosis 1, 2, 3.
  • Reactive thrombocytosis: This occurs in response to inflammation, infection, or other conditions, such as Kawasaki disease 4.
  • Iron deficiency: Iron deficiency can lead to an increase in platelet production, resulting in thrombocytosis.
  • Splenectomy: Removal of the spleen can lead to an increase in platelet count, as the spleen normally removes old or damaged platelets from the circulation.

Other Factors Associated with Thrombocytosis

  • Leukocytosis: An increase in white blood cell count is often associated with MPNs and can contribute to thrombocytosis 1, 2.
  • JAK2V617F mutation: This mutation is commonly found in MPNs and can contribute to thrombocytosis 1, 2.
  • Hormonal factors: Hormonal changes, such as those that occur during pregnancy, can increase the risk of thrombocytosis 1, 3.
  • Inherited thrombophilias: Certain genetic mutations, such as factor V Leiden, can increase the risk of thrombocytosis 3. It is essential to note that the causes of thrombocytosis can vary depending on the individual and the underlying condition. A thorough evaluation and diagnosis by a healthcare professional are necessary to determine the underlying cause of thrombocytosis.

From the Research

Causes of Thrombocytosis

Thrombocytosis can be caused by a variety of factors, including:

  • Primary thrombocytosis, which is often due to essential thrombocythemia (ET) or other myeloproliferative disorders (MPDs) 5
  • Secondary thrombocytosis, which can be caused by:
    • Infections, such as bacterial or viral infections 6, 7, 8
    • Tissue injury or damage 7, 8
    • Chronic inflammatory disorders, such as rheumatoid arthritis or inflammatory bowel disease 7, 8
    • Iron deficiency anemia 7
    • Malignancy or cancer 8
    • Rebound thrombocytosis, which can occur after a period of thrombocytopenia 8
    • Postsplenectomy patients 8

Classification of Thrombocytosis

Thrombocytosis can be classified as:

  • Primary thrombocytosis, which is further divided into:
    • Familial thrombocytosis
    • Essential thrombocytosis (ET)
  • Secondary thrombocytosis, which is also known as reactive thrombocytosis (RT) 9

Clinical Characteristics of Thrombocytosis

Patients with thrombocytosis may present with:

  • Elevated platelet count, which can be mild, moderate, or severe 9
  • Clinical characteristics such as fever, tachycardia, weight loss, hypoalbuminemia, neutrophilia, leukocytosis, and anemia 6
  • Increased risk of thrombosis or bleeding complications, particularly in patients with primary thrombocytosis 5, 7

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.