Evaluation of automated immunoassays in the diagnosis of heparin induced thrombocytopenia.

Karina Althaus, Gregor Hron, Ulrike Strobel, Rosanna Abbate, Angela Rogolino, Simon Davidson, Andreas Greinacher, Tamam Bakchoul

Institute for Immunology and Transfusion Medicine, Ernst-Moritz-Arndt University Greifswald, Germany.

Thrombosis research 2013 Mar

filter terms:

Heparin-induced thrombocytopenia (HIT) is caused by platelet-activating antibodies that recognize platelet factor 4/heparin (PF4/hep) complexes. The in vitro demonstration of PF4/hep antibodies using functional and immunological methods is essential for optimal management of patients suspected to have HIT. Since functional assays are technically challenging and limited to specialized laboratories, antigen-binding assays are commonly used in routine laboratories. Blood samples from 448 consecutive patients in whom HIT was suspected were investigated using a latex agglutination test HemosIL® HIT-Ab(PF4-H) (HemosIL-Ab), two chemiluminescence tests HemosIL AcuStar HIT-Ab(PF4-H) (HemosIL AcuStar-Ab) and AcuStar HIT-IgG(PF4-H) (HemosIL AcuStar-IgG), an in-house PF4/hep IgG enzyme immunoassay (EIA) and the heparin induced platelet aggregation (HIPA) test. Antibodies against PF4/hep were detectable in 44 out of 119 samples using HemosIL-Ab among which 20 samples were also reactive in the HIPA; and in 122, 64 and 108 out of 448 sera using HemosIL AcuStar-Ab, HemosIL AcuStar-IgG and in-house PF4/hep IgG-EIA, respectively, among which 52 sera were also reactive in the HIPA. All assays had high sensitivities of >95% for platelet activating antibodies; however, they differed in their specificities. The highest specificity and positive predictive value was observed by HemosIL AcuStar-IgG (96% and 78%, respectively). Automated immunoassays are useful in the laboratory investigations of HIT and present a potential improvement toward standardization of laboratory investigations of HIT. The high positive predictive capability may justify treating the patient with alternative anticoagulants without waiting for the results of a functional assay. Copyright © 2013 Elsevier Ltd. All rights reserved.

Citation

Karina Althaus, Gregor Hron, Ulrike Strobel, Rosanna Abbate, Angela Rogolino, Simon Davidson, Andreas Greinacher, Tamam Bakchoul. Evaluation of automated immunoassays in the diagnosis of heparin induced thrombocytopenia. Thrombosis research. 2013 Mar;131(3):e85-90