Thrombocytopenia

Overview
  • Thrombocytopenia refers to a state of reduced peripheral platelets and can be caused by a wide variety of etiologies that either decrease platelet production or increase platelet consumption. Whatever the etiology, the primary consequence is mucocutaneous bleeding.
Etiologies
  • Overview
    • Thrombocytopenia can either be caused by reduced platelet production or increased platelet consumption. Before a full workup for thrombocytopenia is initiated, pseudo-thrombocytopenia should be ruled out. Pseudo-thrombocytopenia refers to clumping of platelets and thus erroneously low platelet levels being read on automated blood counts. The presence of psuedo-thrombocytopenia can be assessed by performing a manual peripheral blood smear.
  • Reduced Platelet Production
    • In general, reduced platelet production is the result of generalized marrow suppression and is accompanied by reduced levels of other blood lines. A variety of infectious, neoplastic, and pharmacological causes can be the culprit and we forego a detailed discussion of them here. Common causes include aplastic anemia and myelophthisic anemias.
  • Increased Platelet Consumption
    • Platelets can be consumed by two basic mechanisms: 1) Excess hemostasis and 2) Immune-mediated destruction
    • States of excessive systemic hemostasis can result in severe platelet consumption by inclusion into diffuse clots. This occurs in states such as Microangiopathic Hemolytic Anemia and DIC
    • Antibody binding to platelets and subsequent destruction by the reticuloendothelial system can result in severe thrombocytopenia and occurs in conditions such as ITP and Heparin-induced Thrombocytopenia
Clinical Consequences
  • When mild, thrombocytopenia is largely asymptomatic; however, as a certain threshold is crossed, there develops progressively increased mucocutaneous bleeding. Mucousal bleeding primarily results in gingival bleeding and potentially unremitting epistaxis. Bleeding within the skin initially presents as micro-hemorrhages, manifesting as petechia and ultimately purpura. In women, menorrhagia can result. At critically low levels of platelets, the risk for subarachnoid hemorrhages increases substantially.
Subtopics