Table of ContentsView AllTable of ContentsTypesSymptomsCausesDiagnosisPrognosisFrequently Asked Questions
Table of ContentsView All
View All
Table of Contents
Types
Symptoms
Causes
Diagnosis
Prognosis
Frequently Asked Questions
Platelets are the cells in the body that are activated to help the blood clot and to heal blood vessel walls if they are damaged and bleeding. When there are too many platelets in the blood, this is referred to as thrombocytosis.
A normalplatelet countis 150,000 to 450,000 platelets per microliter (mcL) of blood. A diagnosis of thrombocytosis is made when platelets are higher than 450,000 per mcL.
This article discusses the types, symptoms, causes, and diagnosis of thrombocytosis.
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Types of Thrombocytosis
There are two general types of thrombocytosis:
Thrombocytosis Symptoms
Very commonly, thrombocytosis does not show any symptoms and is found during routine blood work. However, it is possible that some symptoms may be present.
Symptoms may occur due to the platelets not functioning properly and leading to bleeding, while other symptoms may be related to platelets clumping together and causing blood clots.
These symptoms may include:
In primary thrombocytosis, thehigh number of platelets being madeis due to an abnormality in how the bone marrow is making them. This is also referred to as essential thrombocythemia, or ET. The bone marrow may not function normally due to a genetic mutation.
In ET, a mutation may exist in theJAK2gene, which causes an enzyme to work too much at making platelets. A mutation in theCALRgene can also cause too many platelets to be made in the bone marrow.
Secondary thrombocytosis is also called reactive thrombocytosis, as the platelets rise in response to something outside of the bone marrow. Things that may lead to secondary thrombocytosis may include:
Thrombocytosis is often found during routine blood testing, typically acomplete blood count (CBC). This lab test would demonstrate a platelet count above 450,000 per mcL. Other testing that may be ordered to further evaluate the cause of thrombocytosis may include:
Depending on the cause of thrombocytosis, there may be no long-term effects or life-threatening complications from having elevated platelet counts.
However, if there is an underlying condition, such as cancer or another illness, or if complications from having too many platelets occur, these could impact long-term prognosis.
What can cause a high platelet count in children?
What is essential thrombocytosis?
Essential thrombocytosis (ET) is a dysfunction in the bone marrow that causes too many platelets to be made.The cause of ET is not entirely clear, but about 90% of cases have an acquired mutation inJAK2,CALR, orMPL.
What is reactive thrombocytosis?
Reactive thrombocytosis is an elevation in platelet counts for a reason outside of the bone marrow. The platelets increase in reaction to something such as iron deficiency, infection, inflammation, cancer, or bleeding.
A Word From Verywell
Being told that you have high platelets may make you feel anxious or nervous. Remember that the most common cause of high platelets is due to a reactive process. If you continue to be concerned or have additional questions, be sure to reach out to your healthcare team for answers.
8 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Johns Hopkins Medicine.What are platelets and why are they important?National Heart, Lung, and Blood Institute.Thrombocythemia and thrombocytosis.Cleveland Clinic.Thrombocytosis.Brière JB.Essential thrombocythemia.Orphanet J Rare Dis. 2007;2(1):3. doi:10.1186/1750-1172-2-3National Organization for Rare Disorders.Essential thrombocythemia.Watson J, Jones HE, Banks J, Whiting P, Salisbury C, Hamilton W.Use of multiple inflammatory marker tests in primary care: using Clinical Practice Research Datalink to evaluate accuracy.Br J Gen Pract. 2019;69(684):e462-e469. doi:10.3399/bjgp19X704309Kucine N, Chastain KM, Mahler MB, Bussel JB.Primary thrombocytosis in children.Haematologica. 2014;99(4):620-628. doi:10.3324/haematol.2013.092684Tefferi A, Barbui T.Polycythemia vera and essential thrombocythemia: 2021 update on diagnosis, risk‐stratification and management.American J Hematol. 2020;95(12):1599-1613. doi:10.1002/ajh.26008
8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Johns Hopkins Medicine.What are platelets and why are they important?National Heart, Lung, and Blood Institute.Thrombocythemia and thrombocytosis.Cleveland Clinic.Thrombocytosis.Brière JB.Essential thrombocythemia.Orphanet J Rare Dis. 2007;2(1):3. doi:10.1186/1750-1172-2-3National Organization for Rare Disorders.Essential thrombocythemia.Watson J, Jones HE, Banks J, Whiting P, Salisbury C, Hamilton W.Use of multiple inflammatory marker tests in primary care: using Clinical Practice Research Datalink to evaluate accuracy.Br J Gen Pract. 2019;69(684):e462-e469. doi:10.3399/bjgp19X704309Kucine N, Chastain KM, Mahler MB, Bussel JB.Primary thrombocytosis in children.Haematologica. 2014;99(4):620-628. doi:10.3324/haematol.2013.092684Tefferi A, Barbui T.Polycythemia vera and essential thrombocythemia: 2021 update on diagnosis, risk‐stratification and management.American J Hematol. 2020;95(12):1599-1613. doi:10.1002/ajh.26008
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Johns Hopkins Medicine.What are platelets and why are they important?National Heart, Lung, and Blood Institute.Thrombocythemia and thrombocytosis.Cleveland Clinic.Thrombocytosis.Brière JB.Essential thrombocythemia.Orphanet J Rare Dis. 2007;2(1):3. doi:10.1186/1750-1172-2-3National Organization for Rare Disorders.Essential thrombocythemia.Watson J, Jones HE, Banks J, Whiting P, Salisbury C, Hamilton W.Use of multiple inflammatory marker tests in primary care: using Clinical Practice Research Datalink to evaluate accuracy.Br J Gen Pract. 2019;69(684):e462-e469. doi:10.3399/bjgp19X704309Kucine N, Chastain KM, Mahler MB, Bussel JB.Primary thrombocytosis in children.Haematologica. 2014;99(4):620-628. doi:10.3324/haematol.2013.092684Tefferi A, Barbui T.Polycythemia vera and essential thrombocythemia: 2021 update on diagnosis, risk‐stratification and management.American J Hematol. 2020;95(12):1599-1613. doi:10.1002/ajh.26008
Johns Hopkins Medicine.What are platelets and why are they important?
National Heart, Lung, and Blood Institute.Thrombocythemia and thrombocytosis.
Cleveland Clinic.Thrombocytosis.
Brière JB.Essential thrombocythemia.Orphanet J Rare Dis. 2007;2(1):3. doi:10.1186/1750-1172-2-3
National Organization for Rare Disorders.Essential thrombocythemia.
Watson J, Jones HE, Banks J, Whiting P, Salisbury C, Hamilton W.Use of multiple inflammatory marker tests in primary care: using Clinical Practice Research Datalink to evaluate accuracy.Br J Gen Pract. 2019;69(684):e462-e469. doi:10.3399/bjgp19X704309
Kucine N, Chastain KM, Mahler MB, Bussel JB.Primary thrombocytosis in children.Haematologica. 2014;99(4):620-628. doi:10.3324/haematol.2013.092684
Tefferi A, Barbui T.Polycythemia vera and essential thrombocythemia: 2021 update on diagnosis, risk‐stratification and management.American J Hematol. 2020;95(12):1599-1613. doi:10.1002/ajh.26008
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