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Summary
Platelets, also known as thrombocytes, are blood cells. They form in your bone marrow, a sponge-like tissue in your bones. Platelets play a major role in blood clotting. Normally, when one of your blood vessels is injured, you start to bleed. Your platelets will clot (clump together) to plug the hole in the blood vessel and stop the bleeding. You can have different problems with your platelets:
- If your blood has a low number of platelets, it is called thrombocytopenia. This can put you at risk for mild to serious bleeding. The bleeding could be external or internal. There can be various causes. If the problem is mild, you may not need treatment. For more serious cases, you may need medicines or blood or platelet transfusions.
- If your blood has too many platelets, you may have a higher risk of blood clots.
- When the cause is unknown, this is called thrombocythemia. It is rare. You may not need treatment if there are no signs or symptoms. In other cases, people who have it may need treatment with medicines or procedures.
- If another disease or condition is causing the high platelet count, it is thrombocytosis. The treatment and outlook for thrombocytosis depends on what is causing it.
- Another possible problem is that your platelets do not work as they should. For example, in von Willebrand Disease, your platelets cannot stick together or cannot attach to blood vessel walls. This can cause excessive bleeding. There are different types of in von Willebrand Disease; treatment depends on which type you have.
NIH: National Heart, Lung, and Blood Institute
Diagnosis and Tests
- Heparin-Induced Thrombocytopenia Antibody Test (American Association for Clinical Chemistry)
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MPV Blood Test
(National Library of Medicine) Also in Spanish
- Platelet Function Tests (American Association for Clinical Chemistry)
- von Willebrand Factor Test (American Association for Clinical Chemistry)
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What Are Bone Marrow Tests?
(National Heart, Lung, and Blood Institute)
Treatments and Therapies
- Splenectomy (Mayo Foundation for Medical Education and Research) Also in Spanish
-
What Is a Blood Transfusion?
(National Heart, Lung, and Blood Institute)
Related Issues
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Bleeding Disorders
(National Heart, Lung, and Blood Institute) Also in Spanish
Specifics
- Heparin-Induced Thrombocytopenia (American Heart Association) - PDF
- Idiopathic Thrombocytopenic Purpura (ITP) (Mayo Foundation for Medical Education and Research)
-
Immune Thrombocytopenia
(National Heart, Lung, and Blood Institute)
- Information about TTP-HUS (University of Oklahoma Health Sciences Center)
- Inherited Platelet Disorders (World Federation of Hemophilia)
- Petechiae (Mayo Foundation for Medical Education and Research) Also in Spanish
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Thrombocythemia and Thrombocytosis
(National Heart, Lung, and Blood Institute)
-
Thrombocytopenia
(National Heart, Lung, and Blood Institute)
- Thrombocytosis (Mayo Foundation for Medical Education and Research) Also in Spanish
-
Thrombotic Thrombocytopenic Purpura
(National Heart, Lung, and Blood Institute)
Genetics
-
atypical hemolytic-uremic syndrome: MedlinePlus Genetics
(National Library of Medicine)
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Bernard-Soulier syndrome: MedlinePlus Genetics
(National Library of Medicine)
-
dyserythropoietic anemia and thrombocytopenia: MedlinePlus Genetics
(National Library of Medicine)
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essential thrombocythemia: MedlinePlus Genetics
(National Library of Medicine)
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Glanzmann thrombasthenia: MedlinePlus Genetics
(National Library of Medicine)
-
gray platelet syndrome: MedlinePlus Genetics
(National Library of Medicine)
-
Hermansky-Pudlak syndrome: MedlinePlus Genetics
(National Library of Medicine)
-
immune thrombocytopenia: MedlinePlus Genetics
(National Library of Medicine)
-
Jacobsen syndrome: MedlinePlus Genetics
(National Library of Medicine)
-
MYH9-related disorder: MedlinePlus Genetics
(National Library of Medicine)
-
thrombotic thrombocytopenic purpura: MedlinePlus Genetics
(National Library of Medicine)
-
von Willebrand disease: MedlinePlus Genetics
(National Library of Medicine)
-
X-linked thrombocytopenia: MedlinePlus Genetics
(National Library of Medicine)
Videos and Tutorials
-
Blood clotting
(Medical Encyclopedia) Also in Spanish
Clinical Trials
-
ClinicalTrials.gov: Blood Platelet Disorders
(National Institutes of Health)
-
ClinicalTrials.gov: Thrombocytopenia
(National Institutes of Health)
-
ClinicalTrials.gov: von Willebrand Diseases
(National Institutes of Health)
Journal Articles References and abstracts from MEDLINE/PubMed (National Library of Medicine)
- Article: A study of 18F-FLT positron emission tomography/computed tomography imaging in cases...
- Article: Polycythemia vera and essential thrombocythemia: 2021 update on diagnosis, risk-stratification and...
- Article: Three myeloproliferative neoplasms: An overview.
- Platelet Disorders -- see more articles
- Thrombocytopenias -- see more articles
- von Willebrand disease -- see more articles
Find an Expert
- Find a Hematologist (American Society of Hematology)
-
National Heart, Lung, and Blood Institute
Children
- Immune Thrombocytopenia (For Parents) (Nemours Foundation) Also in Spanish
- von Willebrand Disease (For Parents) (Nemours Foundation) Also in Spanish
Patient Handouts
- Bleeding time (Medical Encyclopedia) Also in Spanish
- Congenital platelet function defects (Medical Encyclopedia) Also in Spanish
- Glanzmann disease (Medical Encyclopedia) Also in Spanish
- Idiopathic thrombocytopenic purpura (ITP) (Medical Encyclopedia) Also in Spanish
- Partial thromboplastin time (PTT) (Medical Encyclopedia) Also in Spanish
- Platelet aggregation test (Medical Encyclopedia) Also in Spanish
- Primary thrombocythemia (Medical Encyclopedia) Also in Spanish
- Purpura (Medical Encyclopedia) Also in Spanish
- Thrombocytopenia (Medical Encyclopedia) Also in Spanish
- Thromobocytopenia - drug-induced (Medical Encyclopedia) Also in Spanish