Platelet microparticle generation assay: A valuable test for immune heparin-induced thrombocytopenia diagnosis

BackgroundEarly diagnosis of immune heparin-induced thrombocytopenia (HIT) is essential to improve clinical outcome but remains challenging. The release of platelet microparticles (PMPs) is considered of major pathophysiological significance.ObjectivesThe aim of this study was to evaluate performances of PMP generation assay (PMPGA) compared to clinical outcome to diagnose HIT. The second objective was to compare PMPGA with performances of 14C-serotonin release assay (SRA) on the same series of patients.MethodsSera of 53 HIT-suspected patients were retrospectively incubated with citrated-whole blood from healthy donors with 1 IU and 500 IU/ml of unfractionated heparin (UH). PMPGA was performed using FACSAria® flow cytometer. The clinical diagnosis was established by two blinded independent investigators analysing in a standardized manner the patient's medical records. Performances of PMPGA and SRA (n = 53) were evaluated using ROC curve analysis with clinical outcome as reference.ResultsIn positive HIT patients, PMPs expressing phosphatidylserine are generated with low UH concentration whereas PMP rate decreases significantly in presence of high UH concentration. Using clinical outcome as reference, sensitivity and specificity of PMPGA reached 88.9% (95% CI: 50.7-99.4) and 100.0% (95% CI: 90.0-100.0). Sensitivity and specificity of 14C-SRA were 88.9% (95% CI: 50.7-99.4) and 95.5% (95% CI: 83.3-99.2).ConclusionsPMPGA is a rapid and reliable assay for HIT diagnosis. PMPGA showed good correlation with 14C-SRA performances and predominately with clinical outcome.