Thromboelastography and the Functional Confirmation of Heparin-Induced Thrombocytopenia in Donor Whole Blood

Thromboelastography (TEG) presents a novel testing environment to detect functional antibodies associated with heparin-induced thrombocytopenia (HIT). TEG is considered a qualitative and qualitative method for assess global hemostasis in a test environment that includes shear stresses. In this study we explore the sensitivity of TEG to detect a HIT-associated reaction when whole blood or platelet rich plasma (PRP) is mixed with heat inactivated positive HIT sera in the presence of low dose (0.2U/mL) or high dose (100U/mL) sodium heparin. TEG is designed to record the kinetic changes in whole blood or plasma-based samples during clot initiation, propagation and fibrinolysis. Here we show that HIT positive sera can cause a reaction in both whole blood and PRP when exposed to reactive normal donor whole blood or PRP. Curiously, whole blood was shown to be more sensitive to the presence of HIT positive sera than PRP. The ration of heat-inactivated sera to donor whole blood or PRP was 1 to 2 parts. HIT positive sera was obtained from a patient that was clinical diagnosed with HIT type II and had a clinically significant positive ELISA with an optical density of 1.735 ± 0.032. HIT positive sera with ELISA optical densities above 1.000 or associated with an enhanced likelihood of developing thrombosis. Additionally, the HIT positive sera was functionally positive with 13 qualified, reactive HIT normal platelet donors with a washed-platelet heparin-induced platelet activation (wp-HIPA) average result of 66 ± 11%. The wp-HIPA is an established reference method or GOLD STANDARD assay for the diagnosis of HIT. The positive TEG detection of this functional HIT antibody may reveal another, more rapid test approach for the hospital and reference laboratory diagnosis of HIT. Additional studies are warranted to further characterize the comparative sensitivities of TEG and wp-HIPA and other reference methods for the diagnosis of HIT.