What causes high platelets?

Platelets are made in bone marrow, the tissue located inside of bones. Abnormally high platelet production may occur independently, for reasons that are not known (primary thrombocythemia), or as a symptom of another condition (secondary thrombocytosis).

Causes of high platelets in primary thrombocythemia

Thrombocythemia is a condition in which high platelets occur as an independent condition without another known cause. In this condition, the bone marrow makes too many platelets. This condition may be inherited.

Causes of high platelets in secondary thrombocytosis

Thrombocytosis is the occurrence of high platelets as a symptom of another condition. A wide range of diseases and conditions may cause high platelets including:

  • Anemia (low red blood cell count)
  • Blood loss
  • Cancer
  • Chemotherapy
  • Chronic myelogenous leukemia (type of cancer that develops in the bone marrow, the soft tissue inside bones that helps form blood cells)
  • Infection
  • Inflammatory disorders such as Kawasaki disease (rare childhood disease that involves inflammation of the blood vessels)
  • Myelodysplasia (group of conditions in which the blood cells are abnormal in development or function)
  • Myelofibrosis (disorder that results in scar tissue in the bone marrow)
  • Polycythemia vera (rare bone marrow disorder causing excessive production of blood cells)
  • Reaction to certain medications, including steroids
  • Splenectomy (surgical removal of the spleen)

Questions for diagnosing the cause of high platelets

To diagnose your condition, your doctor or licensed health care practitioner will ask you several questions related to your high platelets including:

  • Are you experiencing any other symptoms, such as weakness or bleeding?
  • What medications are you taking?
  • Have you been diagnosed with any other conditions?

What are the potential complications of high platelets?

Because high platelets can be due to serious diseases, failure to seek treatment can result in serious complications and permanent damage. Once the underlying cause is diagnosed, it is important for you to follow the treatment plan you and your health care professional design specifically for you to reduce the risk of potential complications. Potential complications of high platelets may include:

  • Bleeding
  • Blood clots
  • Brain damage such as stroke


  1. What are thrombocythemia and thrombocytosis? National Heart, Lung, and Blood Institute Diseases and Conditions Index. http://www.nhlbi.nih.gov/health/dci/Diseases/thrm/thrm_what.html.
  2. Primary thrombocythemia. Medline Plus, a service of the National Library of Medicine National Institutes of Health. http://www.nlm.nih.gov/medlineplus/ency/article/000543.htm

What is high platelets?

High platelets is a condition in which the blood contains more platelets than normal. Platelets are small blood cell fragments that assist in blood clotting. In a healthy person, there are usually 150,000 to 450,000 platelets per microliter of blood. A high platelet count can be identified through routine blood tests.

... Read more about high plateletsintroduction


What other symptoms might occur with high platelets?

High platelets may accompany other symptoms, which vary depending on the underlying disease, disorder or condition. However, some people who have high platelets may not experience any other symptoms. In these individuals, high platelets may only be detected through routine blood tests.

People with primary thrombocythemia have a higher risk of bleeding and blood clots than those wi... Read more about high plateletssymptoms

Medical Reviewer: Cynthia Haines, MD Last Annual Review Date: Aug 2, 2013 Copyright: © Copyright 2014 Health Grades, Inc. All rights reserved. May not be reproduced or reprinted without permission from Health Grades, Inc. Use of this information is governed by the HealthGrades User Agreement.

This Article is Filed Under: Heart, Blood and Circulation