Heparin Anti-Xa, Plasma
Use
This test measures heparin concentration in patients treated with low-molecular-weight heparin preparations. It is useful for patients with prolonged baseline activated partial thromboplastin time (APTT) or when an unexpectedly higher dose of unfractionated heparin is needed for desired APTT prolongation. It is not useful for monitoring therapy with the heparinoid 'danaparoid'. The anti-Xa assay is a preferred method for monitoring low-molecular-weight heparin therapy due to its reduced sensitivity to APTT.
Special Instructions
Specimens must be double-centrifuged to avoid platelet contamination, as this may cause erroneous results. Proper specimen handling per Coagulation Guidelines is critical.
Limitations
The test may produce spuriously low results if very low endogenous antithrombin III levels are present. Antibodies to bovine factor X or AT III can interfere with the assay, although this occurrence is rare. Plasma specimens must be thoroughly centrifuged to deplete platelets before freezing to prevent interference from heparin antagonists like platelet factor 4.
FDA ApprovedNew York Approved
Methodology
Other (Chromogenic Method)
Biomarkers
LOINC Codes
- 3274-8
- 3274-8
Result Turnaround Time
1 day
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
1 mL
Minimum Volume
0.5 mL
Container
Light-blue top (3.2% sodium citrate) and Plastic vial
Collection Instructions
Centrifuge, aliquot plasma, and centrifuge plasma again. Aliquot plasma into a plastic vial leaving 0.25 mL in the bottom.
Causes for Rejection
Gross hemolysis
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 2 hours |
| Frozen | 14 days |