Medical College of Wisconsin
CTSICores SearchResearch InformaticsREDCap

A Novel PF4-Dependent Platelet Activation Assay Identifies Patients Likely to Have Heparin-Induced Thrombocytopenia/Thrombosis. Chest 2016 09;150(3):506-15



Pubmed ID


Pubmed Central ID




Scopus ID

2-s2.0-84995622136   36 Citations


BACKGROUND: Almost without exception, patients with heparin-induced thrombocytopenia/thrombosis (HIT) have antibodies that recognize platelet factor 4 (PF4) in a complex with heparin; however, many heparin-treated patients without HIT are also antibody-positive. A platelet activation test, the serotonin release assay (SRA), is useful for identifying a subset of antibodies that are platelet-activating and most likely to cause HIT. However, this "gold standard" assay for HIT diagnosis is technically demanding and is routinely available only through referral laboratories, limiting its availability for timely diagnosis and management.

METHODS: We compared the diagnostic performance of the SRA with that of a technically simple platelet activation assay, the PF4-dependent P-selectin expression assay (PEA), which uses platelets pretreated with PF4 as targets for antibody detection. Archived serum samples from 91 patients for whom clinical information (HIT 4Ts [thrombocytopenia, timing of platelet count fall, thrombosis, and other causes of thrombocytopenia] score) was available were used. Patients with an intermediate 4Ts score and a PF4 ELISA (enzyme-linked immunosorbent assay) optical density ≥ 2.0, or a high 4Ts score and a PF4 ELISA optical density ≥ 1.0, were considered HIT positive; others were designated HIT negative.

RESULTS: The PEA had higher diagnostic accuracy (area under the curve, 0.92 vs 0.82; P = .02) than the SRA, using this definition of HIT. Eleven of 16 serum samples that were PEA positive and SRA negative were HIT positive. Studies done with identical target platelets and serially diluted samples from patients with HIT showed that the PEA is inherently more sensitive than the SRA for the detection of platelet-activating antibodies.

CONCLUSIONS: The PEA is technically less demanding than the SRA and may be more accurate for the diagnosis of HIT.

Author List

Padmanabhan A, Jones CG, Curtis BR, Bougie DW, Sullivan MJ, Peswani N, McFarland JG, Eastwood D, Wang D, Aster RH


Richard H. Aster MD Professor in the Medicine department at Medical College of Wisconsin
Brian Curtis PhD Director in the Platelet & Neutrophil Immunology Laboratory department at BloodCenter of Wisconsin
Demin Wang PhD Assistant Professor in the Microbiology and Immunology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Aged, 80 and over
Case-Control Studies
Enzyme-Linked Immunosorbent Assay
Middle Aged
Platelet Activation
Platelet Factor 4
jenkins-FCD Prod-469 c3fc8ab87196149f9b23743c01b947d47e7319e5