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Test Name:
Heparin Assay
- SBMF No:
25186 - Performance Lab Name:
Hematology - Test Mnemonic:
HEPARIN - ABN:
Not required - CPT Code:
85520 - LOINC Code:
3274-8 - Also Known As:
Heparin Xa Assay, Unfractionated
Unfractionated Heparin Xa Assay - Also See:
25286 Heparin, Low Molecular Weight - Spec Type:
Platelet-poor plasma (PPP) - Spec Container:
Light blue top (3.2% buffered sodium citrate) tube - Pref Vol:
2.0 mL (Two aliquots, 1.0 mL each) - Fasting:
No - Patient Prep:
Collect prior to initiation of anticoagulant therapy - Spec Collect:
- Routine venipuncture
- • NOTE: Traumatic puncture invalidates sample for coagulation studies and necessitates recollection
• Observe proper collection order for coagulation tests; collect tubes for coagulation studies prior to collecting tubes containing clot activators, additives, or anticoagulants
• Fill light blue top tube to stated tube volume
• If coagulation study is only test ordered, collect 1.0 to 2.0 mL blood into tube for discard, then collect light blue top coagulation study tube(s)
• If multiple coagulation studies are requested, submit additional samples for each coagulation test
• Immediately after collection, gently invert tube to mix
- Spec Process:
- Separate plasma from cells immediately
- • Promptly centrifuge 15 minutes
• Carefully transfer plasma portion of sample to separate plastic tube using plastic pipette
• NOTE: Buffy coat layer of sample must be avoided
• Centrifuge transferred plasma sample again to produce platelet-poor plasma (PPP)
• Use second plastic pipette to carefully transfer PPP sample into plastic aliquot tubes
• Immediately freeze PPP samples
- Spec Store Transport:
Frozen - Spec Stability:
4 hours room temperature (20-30°C)
2 weeks frozen (-20°C) – Do not use frost-free units that undergo repeated freeze/thaw cycles - Spec Reject:
Citrate tube underfilled
Sample clotted or hemolyzed
Plasma not frozen within 4 hours of collection - Spec Remarks:
Platelet-poor plasma (PPP) samples obtained by double centrifugation are critical for accurate coagulation studies as platelet contamination may cause spurious results - Methodology:
Spectrophotometry - Use:
Assure that an adequate anticoagulant effect has been achieved
Minimize the risk of bleeding
Monitor for the development of heparin-induced thrombocytopenia - Clinical Significance:
Heparin by itself exhibits little anticoagulant activity. It requires a plasma cofactor, Antithrombin III, for its anticoagulant activity. Specifically, heparin is a catalyst that accelerates the neutralization of activated clotting factors such as Factor Xa and thrombin. The inhibition of Factor Xa by Antithrombin III is accelerated by heparin. Under optimum conditions the amount of Factor Xa activity neutralized during a predetermined time period is directly proportional to the concentration of heparin in the reaction mixture. - Reference Range:
Therapeutic range: 0.3-0.7 U/mL. - Day Run:
Mon-Fri - Time Run:
7:00 am - Time Reported:
5:00 pm - Test Type:
COAGULATION
