Heparin-activated procoagulant platelet assay: a flow cytometry-based functional test for heparin-induced thrombocytopenia.

Background: Functional platelet activation assays are required for the diagnosis of heparin-induced thrombocytopenia (HIT). Due to their sophisticated methodology, they are only available in reference centers.

Objectives: To evaluate the diagnostic accuracy of the flow cytometry-based heparin-activated procoagulant platelet (HAPP) assay in the laboratory diagnosis of HIT.