Coagulation laboratory tests
Heparinase / heparin contamination assay
Reviewer: Jeremy Parsons, M.D. (see Reviewers page)
Revised: 9 February 2013, last major update November 2012
Copyright: (c) 2002-2013, PathologyOutlines.com, Inc.
● To detect heparin contamination of specimens, which may cause a prolonged PTT
● Also used to remove heparin from specimens so coagulation tests can be performed without interference
● Heparinase degrades unfractionated and low molecular weight heparin at multiple sites, including the antithrombin binding site (pentasaccharide sequence), producing fragments up to 1000 daltons, which lack anticoagulant activity
● Measure PTT before and after heparinase (add 1 mL of patient plasma to one vial of heparinase, keep at room temperature for 15 minutes)
● Alternative is to add heparin-binding cellulose to specimens, which binds to heparin, then centrifuge and use supernatant plasma (free of heparin)
● Normal thrombin time rules out heparin prolonging the PTT
● May have coagulation abnormality in addition to heparin contamination
● Marked reduction of PTT, but with elevated value, may indicate residual heparin
● The PTT may never totally correct in normal patients with large amounts of heparin contamination
End of Coagulation > Coagulation laboratory tests > Heparinase / heparin contamination assay
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