A new, rapid, chemiluminescence enzyme assay for the detection of heparin-induced thrombocytopenia: a comparison between functional and immune heparin-induced thrombocytopenia assays.

BACKGROUND

Heparin-induced thrombocytopenia (HIT) is a potentially fatal complication of therapy with unfractionated or low molecular weight heparins that can result in thrombocytopenia and thrombosis. Timely clinical and laboratory diagnoses are imperative to prevent further morbidity and mortality.

OBJECTIVES

To evaluate a rapid high-sensitivity chemiluminescence luminescence enzyme immunoassay (HISCL HIT IgG assay) compared with automated and ELISA antigen assays and heparin-induced platelet activation (HIPA) functional assays on samples healthy donors, patients suspected of having HIT, and other patient subgroups.

METHODS

The HISCL HIT IgG, HemosIL AcuStar HIT-IgG, HemosIL HIT-Ab(PF4-H), Hyphen BioMed ZYMUTEST HIA IgG, and Immucor PF4 IgG assay kits were used to measure plasma and/or serum samples from healthy donors, patients suspected with HIT, and other groups, including patients receiving intensive care, and samples containing potentially interfering substances. All patients suspected with HIT and other HIT-positive results were compared to HIPA functional assay.

RESULTS

Of the 67 HIPA-positive samples, 67 were positive by the HISCL HIT IgG assay. Of the 142 HIPA-negative samples, 104 were negative with the HISCL HIT IgG assay (specificity 73.2%), compared with 97 of 142 negative results with the HemosIL AcuStar HIT-IgG assay (specificity 68.3%). The other assays exhibited lower specificity. The HISCL HIT IgG Assay Kit had no false positive results in samples with potentially interfering substances.

CONCLUSIONS

The HISCL HIT IgG assay had 100% sensitivity and superior specificity compared with other antigen assays. Good correlation was observed between plasma and serum samples, and the time to result was ∼25% faster than the HemosIL AcuStar HIT-IgG assay.