Idiopathic Thrombocytopenic Purpura (ITP)

Overview
  • Idiopathic Thrombocytopenic Purpura (ITP) is an autoimmune disease characterized by development of auto-antibodies to platelets, resulting in an isolated thrombocytopenia in the absence of other blood line defects.
Pathogenesis
  • ITP is caused by the development of IgG auto-antibodies to platelets. Antibody-coated platelets are then recognized by cells of the reticuloendothelial system in the spleen and destroyed, leading to profound thrombocytopenia. As a result, ITP can be thought of as a Type II Hypersensitivity reaction.
  • The precise etiology of this anti-platelet antibody formation is unknown; however, ITP is often associated with antecedant diseases that may derange the immune system. In children, the disease is often preceded by a acute viral infection whereas in adults ITP is often secondary to an underlying chronic disease such as SLE or CLL
Clinical Consequences
  • ITP results in an acute drop in platelet levels, resulting in a thrombocytopenia that is characteristically isolated, meaning that other blood lines such as white cells and red cells are unaffected in numbers or morphology. Patients come to attention due to the classic signs of profound thrombocytopenia, such as epistaxis, petechiae, and ecchymoses. However, splenomegaly is usually not found.
  • In children, ITP is typically self-limited and resolves spontaneously; however, in adults where the disease is often associated with chronic disease, the course is variable and often chronic.