The 2 most prevalent etiologies are ITP and drug-induced thrombocytopenia DITP.
The large extravascular volume of distribution of IgG antibodies, causative in both HIT and VITT, prevents rapid or complete removal via plasma exchange, and the concurrent bleeding complications in VITT may make catheter placement and prolonged apheresis challenging.
A low platelet count is called thrombocytopenia.