Coagulation laboratory tests
Heparinase / heparin contamination assay

Topic Completed: 1 November 2012

Revised: 7 January 2019, last major update November 2012

Copyright: (c) 2002-2016,, Inc.

PubMed Search: Heparinase / heparin contamination assay

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Table of Contents
Definition / general | Diagnosis
Cite this page: Parsons J. Heparinase / heparin contamination assay. website. Accessed July 13th, 2020.
Definition / general
  • 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)

  • Note:
    • 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
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