What is the pathophysiology of immune thrombocytopenia (ITP)?

Updated: Jan 11, 2020
  • Author: Craig M Kessler, MD, MACP; Chief Editor: Srikanth Nagalla, MBBS, MS, FACP  more...
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In immune thrombocytopenia (ITP), an abnormal autoantibody, usually immunoglobulin G (IgG) with specificity for one or more platelet membrane glycoproteins, binds to circulating platelet membranes. [21, 22, 23]

Autoantibody-coated platelets induce Fc receptor-mediated phagocytosis by mononuclear macrophages, primarily but not exclusively in the spleen. [24] The spleen is the key organ in the pathophysiology of ITP, not only because platelet autoantibodies are formed in the white pulp, but also because mononuclear macrophages in the red pulp destroy immunoglobulin-coated platelets. [25]

If bone marrow megakaryocytes cannot increase production and maintain a normal number of circulating platelets, thrombocytopenia and purpura develop. Impaired thrombopoiesis is attributed to failure of a compensatory increase in thrombopoietin and megakaryocyte apoptosis.

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