Coagulation
Coagulation laboratory tests
Heparinase / heparin contamination assay
Author: Jeremy C. Parsons, M.D.
Last author update: 1 November 2012
Last staff update: 22 September 2020
Copyright: 2002-2023, PathologyOutlines.com, Inc.
PubMed Search: Heparinase / heparin contamination assay
Cite this page: Parsons JC. Heparinase / heparin contamination assay. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/coagulationheparinase.html. Accessed November 29th, 2023.
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
Diagnosis
- 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
