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Thrombocytopenia

Definition
1. Decreased Platelet Count
See Also
1. Platelet Dysfunction
2. Purpura
Causes: Platelet Destruction
1. Immune-Mediated
  1. Drug induced Thrombocytopenia
  2. Idiopathic Thrombocytopenic Purpura (ITP)
  3. Post-Transfusion (within 5 to 14 days)
  4. Vasculitis
  5. Autoimmune Hemolytic Anemia
  6. Chronic Lymphocytic Leukemia (CLL)
  7. Systemic Lupus Erythematosus (SLE) in 10% of cases
  8. Lymphoma
  9. Human Immunodeficiency Virus (HIV)
  10. Cytomegalovirus (CMV)
  11. Herpes Virus infection
2. Immune-Mediated in Newborns
  1. Fetal - maternal ABO incompatibility
  2. Neonatal isoimmune or alloimmune Thrombocytopenia
    1. Maternal antibody to fetal platelet antigen (P1)
  3. Neonatal autoimmune Thrombocytopenia
    1. Maternal antibody binds fetal platelets
    2. Maternal conditions
3. Non-immune Mediated
  1. Prosthetic heart valves
  2. Thrombotic Thrombocytopenic Purpura (TTP)
  3. Sepsis
  4. Disseminated Intravascular Coagulation (DIC)
  5. Hemolytic Uremic Syndrome (HUS)
  6. Hemorrhage with extensive transfusion
Causes: Decreased Platelet Production
1. Acquired
  1. Infiltrative process
    1. Leukemia
    2. Histiocytosis
    3. Lymphoma
    4. Myelofibrosis
    5. Storage disease
    6. Neuroblastoma
    7. Granulomatosis
    8. Osteopetrosis
  2. Suppression of Megakaryocytes
    1. Alcoholism
    2. Radiation
    3. Infection (e.g. fetal TORCH Virus infection)
    4. Medications
      1. Alkylating Agents
      2. Antimetabolites
      3. Anticonvulsants
      4. Hydrochlorothiazide or similar Diuretics
      5. Estrogen
    5. Aplastic Anemia
2. Hereditary
  1. Thrombocytopenia-absent radii (TAR syndrome)
    1. Autosomal recessive trait
    2. Purpura immediately or within weeks of birth
  2. Fanconi's Anemia
  3. Wiskott-Aldrich syndrome (x-linked condition)
    1. Decreased platelets (MicroThrombocytopenia)
      1. Adequate Megakaryocytes in Bone Marrow
    2. Eczematous Dermatitis
    3. Repeated infection (Immunodeficiency)
  4. May-Hegglin anomaly
    1. Increased Megakaryocytes
    2. Ineffective thrombopoiesis
  5. Congenital amegakaryocytic Thrombocytopenia
    1. Rare isolated newborn Thrombocytopenia
Causes: Platelet sequestration
1. Splenomegaly
2. Cavernous Hemangioma
Causes: Miscellaneous
1. Pseudothrombocytopenia
2. Dilutional
References

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This page was written by Scott Moses, MD, and was last revised 1/26/2008. Please send comments and questions to the editor. Contact information may be found on the page About the Family Practice Notebook. These pages are best viewed with Microsoft Internet Explorer 5.0.