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Open Access Highly Accessed Research article

Testing for hereditary thrombophilia: a retrospective analysis of testing referred to a national laboratory

Brian R Jackson13*, Kyland Holmes2, Amit Phansalkar3 and George M Rodgers13

Author Affiliations

1 University of Utah Department of Pathology, Salt Lake City, UT, USA

2 ARUP Laboratories, Salt Lake City, UT, USA

3 ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, UT, USA

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BMC Clinical Pathology 2008, 8:3  doi:10.1186/1472-6890-8-3

Published: 2 April 2008

Abstract

Background

Predisposition to venous thrombosis may be assessed through testing for defects and/or deficiencies of a number of hereditary factors. There is potential for confusion about which of these tests are appropriate in which settings. At least one set of recommendations has been published to guide such testing, but it is unclear how widely these have been disseminated.

Methods

We performed a retrospective analysis of laboratory orders and results at a national referral laboratory to gain insight into physicians' ordering practices, specifically comparing them against the ordering practices recommended by a 2002 College of American Pathologists (CAP) consensus conference on thrombophilia testing. Measurements included absolute and relative ordering volumes and positivity rates from approximately 200,000 thrombophilia tests performed from September 2005 through August 2006 at a national reference laboratory. Quality control data were used to estimate the proportion of samples that may have been affected by anticoagulant therapy. A sample of ordering laboratories was surveyed in order to assess potential measurement bias.

Results

Total antigen assays for protein C, protein S and antithrombin were ordered almost as frequently as functional assays for these analytes. The DNA test for factor V Leiden was ordered much more often than the corresponding functional assay. In addition, relative positivity rates coupled with elevations in prothrombin time (PT) in many of these patients suggest that these tests are often ordered in the setting of oral anticoagulant therapy.

Conclusion

In this real-world setting, testing for inherited thrombophilia is frequently at odds with the recommendations of the CAP consensus conference. There is a need for wider dissemination of concise thrombophilia testing guidelines.