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HEPARIN ANTI Xa LOW MOLECULAR WEIGHT HEPARIN
Message- The anti-Xa peak level should be drawn 4 hours after a dose of Enoxaparin is given, once at steady state (at least 3 doses given on time).
- Specimen needs to be centrifuged and aliquoted within 1 hour of collection using the Platelet-Poor technique. See instructions in Additional Information below.
- This test cannot be used to monitor Rivaroxaban (Xarelto) or Fondaparinux (Arixtra) therapy.
Test Code
HXA
Alias/See Also
Anti-10a; Low-Molecular Weight Heparin Assay; Heparin Anti-Xa Assay; Anti-Xa; Heparin Anti-Xa Assay, Plasma; Factor 10a; Factor Xa; FXa; Xa
CPT Codes
85520
Preferred Specimen
1 Blue tube (Sodium Citrate)
Minimum Volume
0.5 mL
Other Acceptable Specimens
None
Instructions
- Centrifuge specimen within one hour of collection.
- Transport 2 mL platelet-poor plasma (minimum 0.5 mL) into a transfer tube. See Additional Information below for instructions on Obtaining A Platelet-Poor Spefcimen.
Transport Container
Standard transport tube
Transport Temperature
Frozen
Specimen Stability
- Plasma separated from cells is stable at 15-30°C up to 4 hours
- -20°C up to 2 weeks
- -70°C up to 6 months
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
The following conditions will result in a rejected sample:
- Serum, EDTA Oxalate, Heparin, or Plasma separator tubes
- Specimens ambient (room temperature) more than 4 hours
- Hemolyzed, icteric, or lipemic specimen
- Specimen submitted refrigerated
- Whole blood specimens not centrifuged within 4 hours
Methodology
Chromogenic Assay
Setup Schedule
M, T, W, R, F, Sa, Su
Report Available
Report available within 24 hours of receipt at the performing laboratory.
Reference Range
| Dosing (Enoxaparin) | Therapeutic Ranges |
| Therapeutic, twice daily dosing | 0.5 1.0 IU/mL |
| Therapeutic, once daily dosing | 1.0 2.0 IU/mL |
| Prophylactic | 0.2 0.5 IU/mL |
If the Heparin Anti-Xa result is high, the patient may be getting an excessive dose and/or not be clearing the drug at an expected rate and may be at an increased risk for excessive bleeding.
If the Heparin Anti-Xa result is below the therapeutic range, then the dosage of heparin may need to be increased to prevent excessive clotting.
Clinical Significance
Assay can be used to monitor patients on Fragmin, Innohep, Lovenox, and Fraxiparine.
Performed By
Alverno Laboratories
Performing Laboratory
Alverno Central Lab
NHMC (Hematology, IL Coag)
Additional Information
Obtaining A Platelet-Poor Specimen
BD Vacutainer Plus Blue Top Volume Guide
Last Updated: June 14, 2023
