Unusual Presentation of Type II Heparin-Induced Thrombocytopenia Successfully Managed with Predilution Online Hemodiafiltration

Introduction: Type II heparin-induced thrombocytopenia (HIT) is portrayed by antibody production against PF4/Heparin complex. While it typically presents with thrombocytopenia and thrombosis, allergic features have also been reported. Predilution Online hemodiafiltration (OL-HDF) can dismiss heparin and is safely used when this anticoagulant is contraindicated. Herein, we present a rare case of type II HIT with wheezing, elevated IgE levels and thrombocytopenia in a dialysis patient effectively handled with predilution OL-HDF. Case Description: An 83-year-old male with unresolved obstructive uropathy was referred to our clinic for dialysis initiation. After four uneventful sessions, he experienced wheezing, 88% oxygen saturation and high filter transmembrane pressures half an hour into the next therapies, despite switch of filter and line brands. Bloodwork revealed 108 k/μL platelets (from 223k/μL), 4Ts score was 6 (high probability) and Anti-PF4/Heparin assay yielded 1.2 U/mL (RR: < 0,6 U/mL), confirming the diagnosis of type II HIT. IgE levels were also elevated at 716 kU/L. Since equipment clotting persisted despite intermitent saline flushes and Apixaban prescription, dialysis therapy was shifted to short daily heparin free predilution OL-HDF. Sessions resumed uneventfully ever since and, six months later, IgE decreased to 296 kU/L, platelets increased to 264k/μL and Anti-PF4/Heparin levels were undetectable, as shown in the graphs attached. Discussion: Type II HIT may display with thrombocytopenia, hypercoagulability and unusual allergic features in a manifold fashion. As management for this condition relies on heparin cessation and clot-preventing strategies, predilution OL-HDF presents a safe and effective dialysis modality in this group of patients.