Heparin-Induced Thrombocytopenia vs. Plasmapheresis- Induced Platelet Loss in a Case of Thrombotic Thrombocytopenic Purpura

Thrombotic thrombocytopenic purpura (TTP) is a clinically heterogeneous syndrome associated with thrombocytopenia, microangiopathic hemolytic anemia, neurologic changes, renal impairment, and fever. The outcome was almost universally fatal until the use of plasma exchange therapy which has dramatically altered the course of disease. Case Report: Here, we report on a 30-year-old female patient suffering from TTP who experienced apheresis treatment resistance. Non-responding thrombocytopenia after initial improvement of neurological symptoms was noted while the patient continued to receive daily plasma exchange therapy (Sartorius Haemoprocessor™). Neither increased volume of plasma exchange nor using cryosupernatant plasma instead of solvent detergent (SD) plasma nor high-dose glucocorticoids lead to a persisting platelet increment. Because of a positive anti-heparin/PF4 antibody gel test we suspected a heparin-induced thrombocytopenia type II (HIT II) developed during plasma exchange therapy. A subsequent non-heparin plasma exchange therapy (COBE Spectra™) with centrifugation technique and citrate as anticoagulant was consequently applied, followed by an increment of the platelet count to normal levels. Additional investigations of the serum with HIT-specific ELISA tests and heparin-induced platelet activation assay (HIPA) turned out to be negative. Eventually it remains unclear to what extent the therapeutical plasma exchanges potentially reduced HIT antibodies and consequently sophisticated the test results. Obviously, the switch to a centrifugal plasmapheresis system using heparin-free anticoagulation was followed by therapeutical success. Conclusion: Platelet loss due to the applied plasmapheresis system as well as potential drug-induced immune thrombocytopenia due to heparin administration during plasma exchange may cause persistent thrombocytopenia in patients with TTP. This may be incorrectly interpreted as continuing active disease, potentially leading to inappropriate additional treatments.