Thrombocytopenia
Low platelet count - thrombocytopeniaThrombocytopenia means there is an abnormally low amount of platelets. Platelets are parts of the blood that help blood to clot. This condition is sometimes associated with abnormal bleeding.
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Causes
Thrombocytopenia is often divided into 3 major causes of low platelets:
- Not enough platelets are made in the bone marrow
- Increased removal of platelets in the bloodstream
- Increased trapping of platelets in the spleen or liver
Your bone marrow may not make enough platelets if you have any of the following conditions:
- Aplastic anemia (disorder in which the bone marrow does not make enough blood cells)
- Cancer in the bone marrow, such as leukemia
- Cirrhosis (liver scarring)
- Folate deficiency
- Infections in the bone marrow (very rare)
- Myelodysplastic syndrome (bone marrow does not make enough blood cells or makes defective cells)
- Vitamin B12 deficiency
Use of certain medicines may also lead to a low production of platelets in the bone marrow. The most common example is chemotherapy treatment for cancer.
The following health situations cause a low number of platelets:
- Disorder in which the proteins that control blood clotting become over active, most often during a serious illness (disseminated intravascular coagulation - DIC)
- Drug-induced low platelet count
- Enlarged spleen
- Disorder in which the immune system destroys platelets (immune thrombocytopenic purpura - ITP)
- Disorder that causes blood clots to form in small blood vessels, causing a low platelet count (thrombotic thrombocytopenic purpura - TTP)
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Symptoms
You may not have any symptoms. Or you may have general symptoms, such as:
- Bleeding in the mouth and gums
- Bruising
- Nosebleeds
- Rash
Other symptoms depend on the cause.
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Exams and Tests
Your health care provider will perform a physical exam and ask about your medical history and symptoms. The following tests may be done:
- Complete blood count (CBC)
- Blood clotting tests: partial thromboplastin time (PTT) and prothrombin time (PT)
Other tests that may help diagnose this condition include bone marrow aspiration or biopsy.
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Treatment
Treatment depends on the cause of the condition. In some cases, a transfusion of platelets may be required to stop or prevent bleeding.
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Outlook (Prognosis)
The outcome depends on the disorder causing the low platelet counts.
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Possible Complications
Severe bleeding (hemorrhage) is the main complication. Bleeding may occur in the brain or gastrointestinal tract.
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When to Contact a Medical Professional
Contact your provider if you experience unexplained bleeding or bruising.
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Prevention
Prevention depends on the specific cause.
References
Abrams CS. Thrombocytopenia. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 158.
Branchford BR, Samelson-Jones BJ, Flood VH. Platelet and blood vessel disorders. In: Kliegman RM, St. Geme JW, Blum NJ, eds. Nelson Textbook of Pediatrics. 22nd ed. Philadelphia, PA: Elsevier; 2025:chap 533.
Warkentin TE. Thrombocytopenia caused by hypersplenism, platelet destruction, or surgery/hemodilution. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 130.
Zeller MP, Ning S, Arnold DM, Gabe C. Diseases of platelet number: immune thrombocytopenia, neonatal alloimmune thrombocytopenia, and posttransfusion purpura. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 129.