Last updated: November 9, 2023

Summarytoggle arrow icon

Thrombocytopenia is a platelet count below the normal range (< 150,000/mm3) that is most commonly due to either impaired platelet production in the bone marrow or increased platelet turnover in the periphery. Common causes of impaired platelet production include bone marrow failure, infection, malignancy, and chemotherapy/radiation. Additional etiologies include hereditary syndromes, such as Wiskott-Aldrich syndrome and Alport syndrome. In contrast, increased peripheral platelet turnover may be caused by autoimmune conditions, (e.g., immune thrombocytopenia), drugs (e.g., heparin), and other conditions (e.g., TTP/HUS, DIC/sepsis). Thrombocytopenia is often asymptomatic and found incidentally on routine bloodwork. Patients may notice petechiae or mucosal bleeding (e.g., bleeding gums, epistaxis) at lower platelet counts. Other patients with thrombocytopenia are clinically ill and have multisystem findings (e.g., acute infection, liver disease, TTP/HUS, DIC). Diagnosis should be confirmed with repeat testing (to rule out pseudothrombocytopenia) and underlying causes should be investigated and treated. Patients with active bleeding or neurological symptoms require emergency platelet transfusion, and in cases of immune-mediated etiologies, IVIG. Observation may be sufficient for patients who have stable medium-low platelet levels and no serious underlying condition. Patients with suspected ITP and low platelet counts (e.g., < 30,000/mm3) are typically treated with corticosteroids, IVIG, or splenectomy.

See also “Immune thrombocytopenia”.

Etiologytoggle arrow icon

Impaired platelet production in bone marrow [1]

Bone marrow conditions → megakaryocytes thrombopoiesis

If platelet production is impaired, the number of megakaryocytes on bone marrow biopsy will also be decreased.

Increased platelet turnover in the periphery

Increased peripheral turnover also increases numbers of megakaryocytes on bone marrow biopsy!

Redistribution, dilution, and other causes


Clinical featurestoggle arrow icon

Clinical features according to platelet count [1][9]
Platelet count Symptoms [9]
  • > 70,000–149,999/mm3
  • Typically: no abnormal bleeding, i.e., asymptomatic thrombocytopenia
  • 20,000–70,000/mm3
  • < 20,000/mm3


Diagnosticstoggle arrow icon

Approach [1]

  • Confirm the diagnosis in all patients:
  • Investigate for underlying causes with a thorough history and routine laboratory studies.
  • If the etiology remains unclear:
    • Evaluate recent medication (see “Etiology”).
    • Order additional investigations based on clinical suspicion, e.g., evaluation for MDS or other malignancies in patients > 60 years old with new-onset thrombocytopenia.
  • See “ITP” if isolated thrombocytopenia with no other underlying cause detected.
  • Evaluate for complications:

Do not delay treatment for diagnostic testing in patients with significant bleeding or new neurological symptoms.

Routine laboratory studies [1]

A rapidly falling platelet count is worrisome, even if it is within the normal range (e.g., in HIT).

Additional investigations

Consider additional laboratory studies or imaging depending on clinical features and results of routine laboratory studies

Additional diagnostic studies for thrombocytopenia by etiology [1][10]
Suspected etiology Supporting clinical features Diagnostics
Autoimmune disease
  • History of autoimmune disease
  • Features of systemic autoimmune diseases, e.g., fever, rash, arthralgia
Heparin-induced thrombocytopenia
HELLP syndrome
Thrombotic microangiopathy
  • TTP
    • Patient is systemically unwell
    • Purpura
    • Neurological features may be seen.
  • HUS
    • Recent gastrointestinal illness, typically with bloody diarrhea
Liver disease and/or hypersplenism

Differential diagnosestoggle arrow icon

See Differential diagnosis of platelet disorders for a comparison of findings in various etiologies of thrombocytopenia.

The differential diagnoses listed here are not exhaustive.

Treatmenttoggle arrow icon

Patients with thrombocytopenia may be asymptomatic or acutely unwell if the thrombocytopenia is a feature of a wider syndrome such as DIC or TTP. Management depends on symptoms, initial platelet count, and the underlying condition.

Approach [1][15]

Emergency management of thrombocytopenia [15][16]

Referencestoggle arrow icon

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  3. Arnold DM, Kukaswadia S, Nazi I, et al. A systematic evaluation of laboratory testing for drug-induced immune thrombocytopenia. Journal of Thrombosis and Haemostasis. 2013; 11 (1): p.169-176.doi: 10.1111/jth.12052 . | Open in Read by QxMD
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  8. Assinger A. Platelets and infection – an emerging role of platelets in viral infection. Front Immunol.. 2014; 5: p.1-12.doi: 10.3389/fimmu.2014.00649 . | Open in Read by QxMD
  9. Caligiuri M, Levi MM, Kaushansky K, et al. Williams Hematology, 9E. McGraw-Hill Education / Medical ; 2015
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  16. Takahashi K, Nagai S, Safwan M, Liang C, Ohkohchi N. Thrombocytopenia after liver transplantation: Should we care?. World Journal of Gastroenterology. 2018; 24 (13): p.1386-1397.doi: 10.3748/wjg.v24.i13.1386 . | Open in Read by QxMD
  17. Neunert C, et al. American Society of Hematology 2019 guidelines for immune thrombocytopenia. Blood Adv. 2019; 3 (23): p.3829-3866.doi: 10.1182/bloodadvances.2019000966 . | Open in Read by QxMD
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  19. Dimitroulis D, et al. Immunological HCV-associated thrombocytopenia: short review.. Clin Dev Immunol. 2012; 2012: p.378653.doi: 10.1155/2012/378653 . | Open in Read by QxMD
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  21. Rodeghiero F, Stasi R, Gernsheimer T, et al. Standardization of terminology, definitions and outcome criteria in immune thrombocytopenic purpura of adults and children: report from an international working group. Blood. 2009; 113 (11): p.2386-2393.doi: 10.1182/blood-2008-07-162503 . | Open in Read by QxMD
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