Evaluation of automated immunoassays in the diagnosis of heparin induced thrombocytopenia

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• 作者：Karina Althaus^a ; Gregor Hron^a ; Ulrike Strobel^a ; Rosanna Abbate^b ; Angela Rogolino^b ; Simon Davidson^c ; Andreas Greinacher^a ; Tamam Bakchoul^a ; ^{tamam.bakchoul@uni-greifswald.de}
• 关键词：Heparin ; thrombocytopenia ; immunoassay
• 刊名：Thrombosis Research
• 出版年：2013
• 出版时间：March, 2013
• 年：2013
• 卷：131
• 期：3
• 页码：e85-e90
• 全文大小：482 K

文摘

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.