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Heparin-induced thrombocytopenia: towards standardization of platelet factor 4/heparin antigen tests.
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2010 (English)In: Journal of Thrombosis and Haemostasis, ISSN 1538-7933, E-ISSN 1538-7836, Vol. 8, no 9, 2025-31 p.Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Laboratory confirmation of heparin-induced thrombocytopenia (HIT) is based on detection of heparin-dependent platelet-activating antibodies. Platelet factor 4 (PF4)/heparin enzyme-immunoassays (EIA) are a widely available surrogate for platelet-activating antibodies.

OBJECTIVE: Defining the optical density (OD) reactivity profiles of a PF4/heparin EIA in reference subject and patient populations and the correlation of the EIA results (expressed in OD units) with the prevalence of platelet-activating antibodies.

PATIENTS/METHODS: Using quantile regression we determined the 97.5th percentile of PF4/heparin-immunoglobulin G (IgG) EIA reactivities in non-heparin-treated individuals [blood donors (n = 935)] and patients before heparin therapy (n = 1207). In patients with suspected HIT, we compared the correlation of EIA-IgG reactivities (Greifswald laboratory; n = 2821) and the heparin-induced platelet activation assay (HIPA) with the correlation of reactivities of another EIA-IgG (McMaster laboratory; n = 1956) with the serotonin-release assay (SRA).

RESULTS: PF4/heparin-IgG EIA OD reactivities had a lower OD 97.5th percentile in blood donors compared with patient groups before heparin treatment (P < 0.001). The percentage of sera testing positive in the functional assays strongly correlated with PF4/heparin-IgG EIA OD reactivities in both laboratories with very similar results (correlation coefficient > 0.9) when normalized OD ranges (maximum OD divided by 10) were used instead of absolute OD values.

CONCLUSIONS: Results of PF4/heparin-IgG EIA should not be reported as only positive or negative as there is no single acceptable cut-off value. Instead, reporting PF4/heparin-IgG EIA OD results in ranges allows for risk-stratified prediction for presence of platelet-activating antibodies. Use of normalized OD ranges permits a standardized approach for inter-laboratory comparisons.

Place, publisher, year, edition, pages
2010. Vol. 8, no 9, 2025-31 p.
National Category
Clinical Medicine
URN: urn:nbn:se:uu:diva-161337DOI: 10.1111/j.1538-7836.2010.03974.xPubMedID: 20626620OAI: oai:DiVA.org:uu-161337DiVA: diva2:455812
Available from: 2011-11-11 Created: 2011-11-11 Last updated: 2011-11-30

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Lubenow, Norbert
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