In the context of the diagnostics of heparin-induced thrombocytopenia, the PF4-heparin ELISA lacks specificity, and the gold standard carbon 14-labeled serotonin release assay (SRA) has its limitations, so the PF4-dependent P-selectin expression assay (PEA) may be the solution for rapid and conclusive testing [46]. Here, PF4 is linked to Thrombocytopenia.