UNUSUAL PRESENTATION OF TYPE II HEPARIN-INDUCED THROMBOCYTOPENIA SUCCESSFULLY MANAGED WITH PREDILUTION ONLINE HEMODIAFILTRATION

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Case Presentation: An 83-year-old male with previously unresolved obstructive uropathy was referred to our clinic for dialysis initiation. After his first four uneventful sessions, he began experiencing pulmonary wheezing, 88% oxygen saturation and high filter transmembrane pressures 30 minutes into the next therapies, despite switch of filter and line brands. Bloodwork revealed 108 k/μL platelets (from 223k/μL at baseline), stable hemoglobin of 11-11.5g/dl and elevated IgE levels at 716 kU/L. Upon suspicion of heparin-induced thrombocytopenia (HIT), The 4T score was calculated, resulting in a total of 6 and indicating high probability for the condition. Anti-Platelet Factor 4/Heparin antibody levels yielded 1.2 U/mL (RR: < 0.6 U/mL), confirming the diagnosis of type II (immune-mediated) HIT. Although symptoms improved with hydrocortisone and bronchodilation therapy in each session, equipment clotting persisted despite intermittent saline flushes and Apixaban prescription, so dialysis therapy was shifted to short daily heparin free predilution online hemodiafiltration (OL-HDF). Sessions resumed uneventfully ever since and, six months later, IgE decreased to 296 kU/L, platelet count increased to 264k/μL and Anti-Platelet Factor 4/Heparin levels were undetectable. DISCUSSION Type II HIT is a serious immune-mediated condition portrayed by antibody production against Platelet Factor 4/Heparin complex. While it typically presents with thrombocytopenia and thrombosis, allergic features have also been reported. Predilution OL-HDF can dismiss heparin in renal replacement therapy and is safely used when this anticoagulant is contraindicated. Here we described a rare case of type II HIT manifesting with wheezing, elevated IgE levels and thrombocytopenia in a dialysis patient effectively handled with predilution OL-HDF. FINAL COMMENTS Type II HIT may display with thrombocytopenia, hypercoagulability and unusual allergic features in a manifold fashion. Early recognition, accurate diagnosis and prompt intervention are crucial to avert severe complications for this complex condition. As management relies on heparin cessation and clot preventing strategies, predilution OL-HDF presents a safe and effective dialysis modality to continue therapy in this group of patients.

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