Evaluation of automated immunoassays in the diagnosis of heparin induced thrombocytopenia

Abstract Background 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 pati...

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Bibliographic Details
Published in:Thrombosis research 2013-03, Vol.131 (3), p.e85-e90
Main Authors: Althaus, Karina, Hron, Gregor, Strobel, Ulrike, Abbate, Rosanna, Rogolino, Angela, Davidson, Simon, Greinacher, Andreas, Bakchoul, Tamam
Format: Article
Language:English
Subjects:
Agglutination
Automation
Hematology, Oncology and Palliative Medicine
Heparin
Heparin - adverse effects
Heparin - chemistry
Humans
immunoassay
Immunoassay - methods
Immunoenzyme Techniques
Immunoglobulin G - chemistry
Latex - chemistry
Luminescence
Platelet Aggregation
Predictive Value of Tests
Reproducibility of Results
Sensitivity and Specificity
thrombocytopenia
Thrombocytopenia - chemically induced
Thrombocytopenia - diagnosis
Thrombocytopenia - immunology
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Summary:Abstract Background 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. Study Design 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. Results 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). Conclusion 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.
ISSN:0049-3848
1879-2472
DOI:10.1016/j.thromres.2013.01.005