Autoimmune HIT due to apheresis catheter heparin flushes for stem-cell harvesting before autotransplantation for myeloma

To the editor: Heparin-induced thrombocytopenia (HIT) is a prothrombotic adverse drug reaction caused by platelet-activating immunoglobulin G (IgG) that recognizes PF4 in complexes with heparin or certain platelet-derived polyanions (chondroitin sulfate and polyphosphates).[1][1][⇓][2]-[3][3] HIT