What is immune thrombocytopenic purpura (ITP)?

Updated: Apr 22, 2018
  • Author: Craig M Kessler, MD, MACP; Chief Editor: Srikanth Nagalla, MBBS, MS, FACP  more...
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Answer

Immune thrombocytopenic purpura (ITP) is a clinical syndrome in which a decreased number of circulating platelets (thrombocytopenia) (see the image below) manifests as a bleeding tendency, easy bruising (purpura), or extravasation of blood from capillaries into skin and mucous membranes (petechiae). Although most cases of acute ITP, particularly in children, are mild and self-limited, intracranial hemorrhage may occur when the platelet count drops below 10 × 109/L (< 10 × 103/µL); [1] this occurs in 0.5-1% of children, and half of these cases are fatal. [2]

Peripheral blood smear from a patient with immune Peripheral blood smear from a patient with immune thrombocytopenic purpura (ITP) shows a decreased number of platelets, a normal-appearing neutrophil, and normal-appearing erythrocytes. ITP is diagnosed by excluding other diseases; therefore, the absence of other findings from the peripheral smear is at least as important as the observed findings. This smear demonstrates the absence of immature leukocytes (as in leukemia) and fragmented erythrocytes (as in thrombotic thrombocytopenic purpura) and no clumps of platelets (as in pseudothrombocytopenia).

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