Table of ContentsView AllTable of ContentsSymptomsReactive ThrombocytosisEssential ThrombocythemiaDiagnosisTreatmentComplications
Table of ContentsView All
View All
Table of Contents
Symptoms
Reactive Thrombocytosis
Essential Thrombocythemia
Diagnosis
Treatment
Complications
A high platelet count indicates too many of the small cells (platelets) that help form blood clots. This can cause dangerous clots and bleeding. Also calledthrombocytosisorthrombocythemia, depending on the cause, a high platelet count is more than 450,000 platelets per microliter of blood.
Essential thrombocythemiadescribes platelet counts rising independently due tobone marrowdysfunction.
Regardless of the cause, a high platelet count can result in dangerous blood clots and bleeding.
Symptoms of a High Platelet Count
Thrombocytosis and thrombocythemia don’t always cause symptoms. For this reason, many people are diagnosed with these conditions after a routine blood test.
If you do have symptoms, they are usually related to the complications of your condition such as blood clots and bleeding. Some of these symptoms may include:
Causes of Reactive Thrombocytosis
Sam Edwards / Getty Images
Reactive thrombocytosis (RT) is also known as secondary thrombocytosis. RT is the more common cause of a high platelet count. With RT, platelet counts are high because of an underlying event or disease.
The causes of RT are described in seven broad categories:
Infections
Infection is the most common cause of a high platelet count in both adults and children.
Soft tissue, lung, gastrointestinal, urinary, and genital infections are the most common infectious causes of RT. Bacterial species or strains commonly associated with these infections include:
Platelet counts generally return to normal after the infection resolves, but this may take several weeks.
Chronic Inflammatory Diseases
Inflammation is the body’s natural response to an infection or injury. When confronted with chronicinflammation, the immune system will increase the production of platelets to aid with the repair of damaged tissues.
Chronic or long-term inflammation is a feature of conditions likechronic obstructive pulmonary disease(COPD) andmyocarditis.
Autoimmune conditions also cause chronic inflammation. When you have an autoimmune condition, your immune system mistakenly attacks your body’s own tissues. Some of the autoimmune diseases associated with high platelets include:
The increase in platelets usually occurs during acute exacerbations (flare-ups) or when the disease is undertreated.
Allergic Conditions
Allergic and atopic conditions associated with high platelet counts include:
Thrombocytosis in these instances tends to be transient and will resolve once the allergy is brought under control.
Anemia
Iron deficiency anemiaoccurs when the lack of iron in the blood causes a decrease in the number, size, and function of red blood cells.
With iron-deficiency anemia, there will be a characteristic drop in red blood cells andhemoglobin(the protein in red blood cells that transport oxygen to cells). For reasons that are not entirely clear, platelet counts will commonly rise when this occurs.
Blood loss, a lack of dietary iron, pregnancy, and intestinal diseases that affect the absorption of iron are the most common causes of iron-deficiency anemia.
Another type of anemia associated with RT ishemolytic anemiain which red blood cells are destroyed as a result of conditions like cancer, hepatitis,sickle cell disease, or certain autoimmune diseases. Again, scientists are not entirely sure why platelets increase as the red blood count decreases.
Asplenia
Aspleniais the lack of aspleen. The spleen works as a blood filter, removing oldred blood cellsand holding onto a reserve of other blood cells in the event of an emergency, such as ahemorrhage.
All told, roughly one-third of the body’s total platelets are stored in the spleen at any one time.
If your spleen stops functioning properly—due to a condition like sickle cell disease or an injury—or is surgically removed (splenectomy), your platelet count can increase to compensate for the loss of its reserve.
Medications
Drugs associated with an increased risk of RT include:
Cancer
RT is common with many forms of cancer. Particularly with solid tumor cancers, the progression of the disease will often trigger an associative increase in platelets, referred to asparaneoplastic thrombocytosis.
These increases can be extreme when a cancer hasmetastasized(spread to distant parts of the body). Paraneoplastic thrombocytosis can occur with all types of cancer but is more common in some cancers than others.
Cancers more likely to cause high platelets include:
Causes of Essential Thrombocythemia
Micro Discovery / Getty Images
Essential thrombocythemia belongs to a group of rare blood cancers calledmyeloproliferative neoplasms, which cause the bone marrow to produce too many blood cells. With essential thrombocythemia, too many platelets are produced.
ET is rare, affecting only around three of every 100,000 people annually.Studies suggest that more than half of all people with ET have a specific mutation of a gene calledJAK2.
ET is a slowly progressive disease with long periods with no symptoms. When symptoms do develop, they tend to manifest with bleeding or blood clots (in some cases causingdeep vein thrombosisorpulmonary embolism). In rare instances, ET can progress toacute myeloid leukemia (AML).
ET is more common in older adults, especially females, and is rarely seen in children.
How High Platelets Are Diagnosed
Thrombocythemia and thrombocytosis are typically identified during routine blood testing, often in the absence of other symptoms. Tests that may discover high platelet count include:
A healthcare provider will do a physical examination for signs of bleeding, bruising, an enlarged spleen, and other symptoms.
Treating Thrombocytosis
Reactive thrombocytosisrarely requires treatment. High platelet count usually returns to normal once the underlying condition causing it (e.g., infection, cancer, inflammation) is resolved.
Treatment foressential thrombocythemiacan include:
Essential thrombocythemia has no cure, but the condition can be managed to reduce clot risk.
Complications of a High Platelet Count
Thrombocytosis and thrombocythemia can cause serious complications such as blood clots. Blood clots can restrict blood flow to your organs, including your brain and heart. This can lead to life-threatening conditions such as:
Thrombocytosis and thrombocythemia can also put you at risk for bleeding. This can happen when blood clots use too many of the platelets in your body. The lack of platelets can put you at higher risk for bleeding when you become injured or there is a break in the wall of a blood vessel.
Bleeding can also occur if you have abnormal platelets that don’t clot the way they are supposed to.
High Platelet Count During PregnancyIf you have a high platelet count during pregnancy, it can cause blood clots that can block blood flow to the fetus.This can cause serious problems like slow fetal growth, miscarriage, or preterm delivery.If you have thrombocytosis during pregnancy, you will likely need to take medications to help lower your platelet count during pregnancy and immediately afterward.
High Platelet Count During Pregnancy
If you have a high platelet count during pregnancy, it can cause blood clots that can block blood flow to the fetus.This can cause serious problems like slow fetal growth, miscarriage, or preterm delivery.If you have thrombocytosis during pregnancy, you will likely need to take medications to help lower your platelet count during pregnancy and immediately afterward.
Summary
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18 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.Kongmee I, Norasetthada L, Tantiworawit A, et al.Prevalence, causes and outcomes of thrombocytopenia among patients in medical intensive care units.Yeaman MR.The role of platelets in antimicrobial host defense.Platelets. 2019:523-46. doi:10.1016/B978-0-12-813456-6.00029-1National Heart, Lung, and Blood Institute.Platelet Disorders - Causes and Risk Factors.Page C, Pitchford S.Platelets and allergic inflammation.Clin Exp Allergy. 2014;44(7):901-913. doi:10.1111/cea.12322World Health Organization.Anaemia.National Heart, Lung, and Blood Institute.Thrombocytopenia.Chia TL, Chesney TR, Isa D, et al.Thrombocytosis in splenic trauma: In-hospital course and association with venous thromboembolism.Injury. 2017;48(1):142-147. doi:10.1016/j.injury.2016.07.016Vo QT, Thompson DF.A review and assessment of drug-induced thrombocytosis.Annals of Pharmacotherapy. 2019;53(5):523-536. doi:10.1177/1060028018819450Giannakeas V, Kotsopoulos J, Cheung MC, et al.Analysis of Platelet Count and New Cancer Diagnosis Over a 10-Year Period.JAMA Netw Open. 2022;5(1):e2141633. Published 2022 Jan 4. doi:10.1001/jamanetworkopen.2021.41633Tefferi A, Pardanani A.Essential thrombocythemia.N Engl J Med. 2019;381(22):2135-2144. doi:10.1056/NEJMcp1816082Tefferi A, Barbui T.Polycythemia vera and essential thrombocythemia: 2021 update on diagnosis, risk-stratification and management.Am J Hematol. 2020;95(12):1599-1613. doi:10.1002/ajh.26008Watson 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/bjgp19X704309Merck Manual (Professional).Essential Thrombocythemia - Diagnosis of Essential Thrombocythemia.Baelum JK, Moe EE, Nybo M, Vinholt PJ.Venous thromboembolism in patients with thrombocytopenia: Risk factors, treatment, and outcome.Clin Appl Thromb Hemost. 2017;23(4):345-350. doi:10.1177/1076029615613158National Heart, Lung, and Blood Institute.Pregnancy and platelet disorders.İskender D, Yılmaz-Ergani S, Aksoy M, et al.High rate of obstetric complications in patients with essential thrombocythemia.Cureus. 2021;13(12):e20449. doi:10.7759/cureus.20449
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.Kongmee I, Norasetthada L, Tantiworawit A, et al.Prevalence, causes and outcomes of thrombocytopenia among patients in medical intensive care units.Yeaman MR.The role of platelets in antimicrobial host defense.Platelets. 2019:523-46. doi:10.1016/B978-0-12-813456-6.00029-1National Heart, Lung, and Blood Institute.Platelet Disorders - Causes and Risk Factors.Page C, Pitchford S.Platelets and allergic inflammation.Clin Exp Allergy. 2014;44(7):901-913. doi:10.1111/cea.12322World Health Organization.Anaemia.National Heart, Lung, and Blood Institute.Thrombocytopenia.Chia TL, Chesney TR, Isa D, et al.Thrombocytosis in splenic trauma: In-hospital course and association with venous thromboembolism.Injury. 2017;48(1):142-147. doi:10.1016/j.injury.2016.07.016Vo QT, Thompson DF.A review and assessment of drug-induced thrombocytosis.Annals of Pharmacotherapy. 2019;53(5):523-536. doi:10.1177/1060028018819450Giannakeas V, Kotsopoulos J, Cheung MC, et al.Analysis of Platelet Count and New Cancer Diagnosis Over a 10-Year Period.JAMA Netw Open. 2022;5(1):e2141633. Published 2022 Jan 4. doi:10.1001/jamanetworkopen.2021.41633Tefferi A, Pardanani A.Essential thrombocythemia.N Engl J Med. 2019;381(22):2135-2144. doi:10.1056/NEJMcp1816082Tefferi A, Barbui T.Polycythemia vera and essential thrombocythemia: 2021 update on diagnosis, risk-stratification and management.Am J Hematol. 2020;95(12):1599-1613. doi:10.1002/ajh.26008Watson 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/bjgp19X704309Merck Manual (Professional).Essential Thrombocythemia - Diagnosis of Essential Thrombocythemia.Baelum JK, Moe EE, Nybo M, Vinholt PJ.Venous thromboembolism in patients with thrombocytopenia: Risk factors, treatment, and outcome.Clin Appl Thromb Hemost. 2017;23(4):345-350. doi:10.1177/1076029615613158National Heart, Lung, and Blood Institute.Pregnancy and platelet disorders.İskender D, Yılmaz-Ergani S, Aksoy M, et al.High rate of obstetric complications in patients with essential thrombocythemia.Cureus. 2021;13(12):e20449. doi:10.7759/cureus.20449
Johns Hopkins Medicine.What are platelets and why are they important?
National Heart, Lung, and Blood Institute.Thrombocythemia and thrombocytosis.
Kongmee I, Norasetthada L, Tantiworawit A, et al.Prevalence, causes and outcomes of thrombocytopenia among patients in medical intensive care units.
Yeaman MR.The role of platelets in antimicrobial host defense.Platelets. 2019:523-46. doi:10.1016/B978-0-12-813456-6.00029-1
National Heart, Lung, and Blood Institute.Platelet Disorders - Causes and Risk Factors.
Page C, Pitchford S.Platelets and allergic inflammation.Clin Exp Allergy. 2014;44(7):901-913. doi:10.1111/cea.12322
World Health Organization.Anaemia.
National Heart, Lung, and Blood Institute.Thrombocytopenia.
Chia TL, Chesney TR, Isa D, et al.Thrombocytosis in splenic trauma: In-hospital course and association with venous thromboembolism.Injury. 2017;48(1):142-147. doi:10.1016/j.injury.2016.07.016
Vo QT, Thompson DF.A review and assessment of drug-induced thrombocytosis.Annals of Pharmacotherapy. 2019;53(5):523-536. doi:10.1177/1060028018819450
Giannakeas V, Kotsopoulos J, Cheung MC, et al.Analysis of Platelet Count and New Cancer Diagnosis Over a 10-Year Period.JAMA Netw Open. 2022;5(1):e2141633. Published 2022 Jan 4. doi:10.1001/jamanetworkopen.2021.41633
Tefferi A, Pardanani A.Essential thrombocythemia.N Engl J Med. 2019;381(22):2135-2144. doi:10.1056/NEJMcp1816082
Tefferi A, Barbui T.Polycythemia vera and essential thrombocythemia: 2021 update on diagnosis, risk-stratification and management.Am J Hematol. 2020;95(12):1599-1613. doi:10.1002/ajh.26008
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
Merck Manual (Professional).Essential Thrombocythemia - Diagnosis of Essential Thrombocythemia.
Baelum JK, Moe EE, Nybo M, Vinholt PJ.Venous thromboembolism in patients with thrombocytopenia: Risk factors, treatment, and outcome.Clin Appl Thromb Hemost. 2017;23(4):345-350. doi:10.1177/1076029615613158
National Heart, Lung, and Blood Institute.Pregnancy and platelet disorders.
İskender D, Yılmaz-Ergani S, Aksoy M, et al.High rate of obstetric complications in patients with essential thrombocythemia.Cureus. 2021;13(12):e20449. doi:10.7759/cureus.20449
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