High platelet counts can occur in patients with polycythemia vera (high red blood cell counts), and is an additional risk factor for complications.A very small number of people report symptoms of erythromelalgia, a burning sensation and redness of the extremities that resolves with cooling, or aspirin or both.Scientific literature sometimes excludes thrombocytosis from the scope of thrombophilia by definition, but practically, by the definition of thrombophilia as an increased predisposition to thrombosis, thrombocytosis (especially primary thrombocytosis) is a potential cause of thrombophilia. Conversely, secondary thrombocytosis very rarely causes thrombotic complications. Causes
Reactive thrombocythemia is the most common cause of a high platelet count. It accounts for 88% to 97% of thrombocythemia cases in adults, and near 100% in children. In adults, acute infection, tissue damage, chronic inflammation and malignancy are the common causes of reactive thrombocythemia. Usually, one or more of these conditions is present in more than 75% of the cases with reactive thrombocythemia. Causes for reactive thrombocythemia in children are similar to adults. In addition, hemolytic anemia and thalassemia are often present in children living in the Middle East. Other causes of reactive thrombocythemia include: post surgery, iron deficiency, drugs, and rebound effect after bone marrow suppression.The SARS disease caused thrombocytosis.Once the reactive causes of thrombocythemia are ruled out, clonal thrombocythemia should be considered. The most common cause of clonal thrombocythemia is a myeloproliferative neoplasm. These include: essential thrombocythemia, chronic myelogenous leukemia, polycythemia vera, and primary myelofibrosis.Extremely rare causes of thrombocythemia are spurious causes.
This is due to the presence of structures resembling platelets in the blood such as needle-like cryoglobulin crystals, cytoplasmic fragments of circulating leukemic cells, bacteria, and red blood cell microvesicles. These structures are counted as platelets by the automated machine counter; therefore, causing the platelet number to be falsely elevated. However, such error can be avoided by doing a peripheral blood smear. Diagnosis
Laboratory tests might include: full blood count, liver enzymes, renal function and erythrocyte sedimentation rate.If the cause for the high platelet count remains unclear, bone marrow biopsy is often undertaken, to differentiate whether the high platelet count is reactive or essential. Treatment
Often, no treatment is required or necessary for reactive thrombocytosis. In cases of reactive thrombocytosis of more than 1,000x109/L, it may be considered to administer daily low dose aspirin (such as 65 mg) to minimize the risk of stroke or thrombosis.However, in essential thrombocythemia where platelet counts are over 750x109/L or 1,000x109/L, especially if there are other risk factors for thrombosis, treatment may be needed. Selective use of aspirin at low doses is thought to be protective. Extremely high platelet counts can be treated with hydroxyurea (a cytoreducing agent) or anagrelide (Agrylin).In Janus kinase 2 positive disorders, ruxolitinib (Jakafi) can be effective. References
Schafer AI (March 2004). "Thrombocytosis". N. Engl. J. Med. 350 (12): 1211–9. doi:10.1056/NEJMra035363. PMID 15028825. == External links ==