Thrombotic microangiopathies (TTP, HUS, HELLP).

Thrombocytopenia, strictly defined as a platelet count less than 150,000, is common in the emergency department. Recognition, diagnostic investigation, and proper disposition of a thrombocytopenic patient are imperative. One group of disorders leading to thrombocytopenia is the thrombotic microangiopathies, hallmarked by platelet destruction. These thrombotic microangiopathies include thrombotic thrombocytopenic purpura (TTP), hemolytic uremic syndrome (HUS) and hemolysis, elevated liver enzyme levels, low platelet count (HELLP), which should be distinguished from similar disease processes such as immune thrombocytopenia (ITP), disseminated intravascular coagulation (DIC) and heparin induced thrombocytopenia (HIT). In this article, clinical presentations, pathophysiology, diagnostic workup, management plans, complications, and dispositions are addressed for this complex group of platelet disorders.