Thrombocytopenia is defined as a low circulating platelet count (<150,000 per microliter). Platelet life span is normally approximately 5 days, with continual renewal. True thrombocytopenia results from either a reduced production of platelets in the bone marrow, increased clearance, or sequestering of platelets in the spleen.
The causes of thrombocytopenia are diverse, making epidemiologic generalizations difficult. However, immune thrombocytopenia (ITP) is typically an illness of young women. The apparent appearance of ITP in other patient groups should prompt a high index of suspicion for an alternate diagnosis: for example, non-Hodgkin lymphoma, drug effect, or myelodysplastic syndrome.
A complete history, physical exam, review of the CBC, and peripheral smear are necessary to narrow down the differential diagnosis of thrombocytopenia. It is important to exclude artifact or pseudothrombocytopenia.
- Metastatic malignancy
- Hodgkin lymphoma
- Non-Hodgkin lymphoma
- Miliary tuberculosis
- Disseminated intravascular coagulation (DIC)
- Hemolysis, elevated liver enzymes, low platelet count (HELLP)
- Cardiopulmonary bypass
- Immune thrombocytopenia (ITP)
- Systemic lupus erythematosus (SLE)
- Rheumatoid arthritis
- Antiphospholipid syndrome
- Cytomegalovirus (CMV)
- Heparin-induced thrombocytopenia (HIT)
- Antimalarials, antiseizure drugs, antibiotics, or chemotherapies
- Alcohol ingestion
- B12 deficiency
- Folate deficiency
- Gestational thrombocytopenia
- Multiple myeloma
- Bone marrow fibrosis
- Thrombotic thrombocytopenic purpura (TTP)
- Hemolytic uremic syndrome (HUS)
- Cyclic thrombocytopenia
- Wiskott-Aldrich syndrome
- MYH9-related disorders, including May-Hegglin anomaly
- Bernard-Soulier syndrome
- Gaucher disease
- Hashimoto thyroiditis
- Aplastic anemia
- Paroxysmal nocturnal hemoglobinuria (PNH)
- Familial platelet disorder with germline RUNX1 mutation
- Thrombocytopenia due to germline ANKRD26 mutation
- Thrombocytopenia due to germline ETV6 mutation
Weill Cornell Medicine
Pathology and Laboratory Medicine
Division of Immunopathology
JTG declares that she has no competing interests.
Dr Julia T. Geyer would like to gratefully acknowledge Dr Alan E. Lichtin, a previous contributor to this monograph. AEL is on an advisory board and has received research support from Amgen.
Clinical Professor of Medicine
University of Texas Health Science Center
Cancer Care Network of South Texas
RML declares that he has no competing interests.
Clinical Assistant Professor of Medicine
University of Connecticut School of Medicine
JSW has received research support from Amgen, Ligand Pharmaceuticals, and MGI Pharma for clinical studies in immune thrombocytopenic purpura.
Professor of Medicine
Case Western Reserve University School of Medicine
KRM declares that he has no competing interests.
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