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Anti Factor Xa

Important Note

Specimen must be in lab and tested within 4 hours of collection.

Direct oral anticoagulants (DOACs) such as rivaroxaban, apixaban, edoxaban, positively interfere with anti-Xa testing.  DOACs prescribed concurretntly with LMWH or UFH can produce falsely elevated LMWH/UFH activity levels

Additional Codes

LAB5416

Performing Laboratory

MBMC Main Laboratory

Methodology

Chromogenic Assay

Literature References:

Package insert: HemosIL Liquid Anti Xa, Instrumentation Laboratory, November 2011

Specimen Requirements

Call Missouri Baptist Medical Center Laboratory Customer Support at 314-996-4522 prior to collection.

 

Specimen must arrive and be tested within 4 hours of draw.

 

Specimen Type: Plasma
Container/Tube: 2.7-mL, light blue-top (sodium citrate) tube
Specimen Volume: Full tube
Collection Instructions: If unable to send STAT, spin down, separate plasma from cells, and freeze.

 

Specimen Transport Temperature

Ambient <4 hours/Frozen OK

Day(s) Test Set Up

Monday through Sunday

Turnaround Time:
STAT: 1 hour from receipt in laboratory

Reference Values

Anti-Xa Interpretive Data

Enoxaparin therapeutic range (peak):

VTE treatment, Q12hr dosing: 0.60-1.00 IUnits/mL

VTE treatment, Q24hr dosing: 1.00-2.00 IUnits/mL

Q24hr dosing for renal impairment (CrCl <30 mL/min): 0.60-1.00 IUnits/mL

VTE prevention: 0.10-0.40 IUnits/mL

 

Anti-Xa therapeutic ranges apply to blood samples drawn 4 hours after last dose (peak).

 

Unfractionated heparin (UFH) therapeutic range: 0.30-0.70 IUnits/mL

 

Direct factor Xa inhibitors (rivaroxaban, apixaban): Results must be interpreted qualitatively. No activity detected suggests little anticoagulant activity.

 

In severe antithrombin deficiency, anti-Xa measurement may be inaccurate.

 

Interpretive guidelines developed in adult populations. Interpretive guidelines for pediatric patients have not been rigorously defined.

Alert Value: >2.00 I U/mL

Test Classification and CPT Coding

Test Classification:

This test has been cleared or approved by the U.S. Food and Drug Administration and is used per manufacturer’s instructions.

CPT Code:

85520 

Stability

4 hours Ambiant temperature