Why do patients with immune thrombocytopenia (ITP) experience lower bleeding events despite thrombocytopenia?

Immune thrombocytopenia is an autoimmune condition characterized by an isolated thrombocytopenia. Despite the low platelet levels, severe bleeding episodes are relatively rare suggesting that patients with ITP may have a protective factor against bleeding. Platelet microparticles (PMP) are thought to play a role in clot formation and some studies have demonstrated higher levels of circulating PMP in patients with ITP. This article provides a review of the epidemiology, mechanism, clinical presentation, management, and prognosis of ITP as well as a review of the literature and discussion regarding PMP and bleeding risk in ITP patients. •Immune thrombocytopenia (ITP) is characterized by increased platelet destruction and suppression of production•ITP has various pathogenetic mechanisms and it is a diagnosis of exclusion•Evidence showed antiplatelet antibodies bind to megakaryocytes and may lead to suppression of platelet production•Despite the severe thrombocytopenia that is often accompanied with ITP, bleeding manifestations are not common•We hypothesize that patients with ITP have higher levels of circulated platelet microparticles that protect against bleeding.