Laboratory testing for heparin-induced thrombocytopenia is inconsistent in North America: A survey of North American specialized coagulation laboratories

Elizabeth A. Price; Catherine P. M. Hayward; Karen A. Moffat; Jane C. Moore; Theodore E. Warkentin; James L. Zehnder

doi:10.1160/TH07-06-0401

Thrombosis and Haemostasis, Table of Contents

Thromb Haemost 2007; 98(06): 1357-1361
DOI: 10.1160/TH07-06-0401

New Technologies, Diagnostic Tools and Drugs

Schattauer GmbH

Laboratory testing for heparin-induced thrombocytopenia is inconsistent in North America: A survey of North American specialized coagulation laboratories

Authors

Elizabeth A. Price

¹Department of Medicine, and
Catherine P. M. Hayward

²Department of Pathology and Molecular Medicine, and

³Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
Karen A. Moffat

³Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada

⁴Department of Coagulation, Hamilton Regional Laboratory Medicine Program, Hamilton, Ontario, Canada
Jane C. Moore

²Department of Pathology and Molecular Medicine, and

³Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
Theodore E. Warkentin

²Department of Pathology and Molecular Medicine, and

³Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
James L. Zehnder

¹Department of Medicine, and

⁵Department of Pathology, Stanford University, Stanford, California, USA

Abstract

Summary

Heparin-induced thrombocytopenia (HIT) is a serious complication of heparin therapy. As HIT is considered a clinico-pathologic entity, laboratory practices have an important role in diagnosing or excluding HIT. It was the objective of this study to assess the current status of laboratory testing for HIT in North America. An online survey consisting of 67 questions related to laboratory testing for HIT was developed by the North American Specialized Coagulation Laboratory Association (NASCOLA), and distributed to its 59 members. The survey included queries about HIT test ordering practices, HIT immunoassay and activation assays performed, and reporting practices. Data was collected from the 44 NASCOLA laboratories who responded. Of these sites, 88% performed immunoassays for HIT, commonly using commercial assays. However, sites varied in practices related to use of controls, immunoglobulin class of antibody detected, and in result interpretation and reporting. Platelet activation assays for HIT were performed by 36% of sites, commonly using assays of serotonin release (50%) or heparin- induced platelet aggregation (43%). Sites varied in the use of washed platelets versus platelet-rich plasma, controls, and heparin concentrations. This survey is the first comprehensive assessment of patterns of practice in HIT testing among diagnostic coagulation laboratories in North America. We observed sitespecific variability of testing methods encompassing all stages of testing, including pre-analytical handling, testing methodologies, and result interpretation and reporting. The variability in HIT platelet activation assay methods among institutions indicates a need for proficiency testing to assess assay performance,and for consensus guidelines on HIT laboratory testing.

Keywords

Heparin-induced thrombocytopenia - laboratory diagnosis - platelet-factor 4 - thrombocytopenia

Full Text

References

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