Apixaban Assay (Anti Xa)

Label Mnemonic: APXAB
Epic code: LAB8857
Order form: Laboratory Requisition
Supply order: Supply Order Form
Billing: Billing Policies
CPT code: 85130
Specimen(s):
Plasma More information
Collection Medium:
or
Light Blue top tube 2.7 mL (Na Citrate) Light Blue top tube 1.8 mL (Na Citrate)
Minimum:

Full draw; 2.7 mL light blue top or 1.8 mL light blue top (mix well)

Testing Schedule:
24 hrs/day, 7 days a week, including holidays.
Turn Around Time:

1-2 hours (upon receipt in laboratory)

Comments:

This assay is not specific for apixaban. Any drug with anti-Xa activity, such as heparin, enoxaparin, rivaroxaban, edoxaban, or betrixaban will cross-react to give a measurable concentration for apixaban.

A therapeutic range has not been established for apixaban. Therapeutic ranges derived from published literature are variable and are not well correlated with safety, efficacy, or clinical outcomes. Plasma concentrations for apixaban have been reported in two clinical trials (median, 5th to 95th percentile shown):

Aristotle trial
2.5 mg twice daily dose: Cmax 123 ng/mL (68.5 - 221 ng/mL)
5 mg twice daily dose: Cmax 171 ng/mL (91 - 321 ng/mL)

AMPLIFY trial
2.5 mg twice daily dose: Cmax 67 ng/mL (29.7 - 153.2 ng/mL)
5 mg twice daily dose: Cmax 132 ng/mL (58.6 - 302.2 ng/mL)

Plasma levels should not be used to determine if a patient is adequately or overly anticoagulated. The use of this test should be limited to the following:

1. Measurement of anti-Xa activity in patients undergoing
   emergent/urgent surgical procedures or with life threatening
   bleeding associated with apixaban use
2. Assessment of level in a patient who is expected to have been 
   non-adherent/non-compliant


This testing was developedN and its performance characteristics determined by the University of Iowa Emory Warner Pathology Laboratories. It has not been cleared or approved by the FDA. The laboratory is regulated under CLIA as qualified to perform high-complexity testing. This test is used for clinical purposes. It should not be regarded as investigational or for research.

References:
Aristotle trial (Circulation 2015;132:624-632)
AMPLIFY trial (N Engl J Med. 2013;369:799 - 808)
Douxfil J, et al J Thromb Haemostat 2018;16:209-219
Wright C, et al Int J Lab Hematol 2017;39:31-36
Samuelson BT, et al Blood Rev 2017;31:77-84

Instrumentation changed from BCS-XP to CS-5100 on 12/16/2019.

Methodology:

Anti Xa activity by chromogenic substrate

Sample Processing:
Double-centrifuge specimen to prepare platelet-free plasma.
Immediately centrifuge specimen at 3500 RPM for 12 minutes.
Using a plastic transfer pipette, carefully remove plasma from cells avoiding the platelet/buffy coat.
Place plasma into a labeled plastic tube.
Centrifuge plasma again at 3500 RPM for 12 minutes.
Remove the top of the plasma and place into a labeled plastic tube.
Freeze double-spun plasma within 4 hours of collection time at -20 degrees C or below.
Sample Storage:
Freeze specimen immediately.
Transport Instructions:
Place labeled specimen into zip-lock type biohazard bag; seal bag.
Place requisition into outside pocket of bag.
Place dry ice on top of specimen in Styrofoam container.
Samples received thawed will be cancelled.
 
See Additional Information:
Hemolysis Chart
Phlebotomy Tubes and Order of Draw
Impact of Common Anticoagulants on Coagulation Tests