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Test Code APIX Apixaban Level by Anti-Xa

Specimen and Container/Tube

Specimen Type: Plasma

Preferred Specimen: Light Blue Top Tube, 3.2% Sodium Citrate

Other Acceptable specimens: N/A

Specimen Handling and Transport Instructions

UCMC Onsite Instructions: 

Collect specimen per standard collection procedure and send to laboratory immediately. 

 

NOTE: Once each blue top tube is completely filled, gently invert the sample tube at least five times to ensure complete mixing of the contents.

 

UCMC Offsite and UC MedLab Outreach Instructions: 

  • Collect specimen per standard collection procedure.
  • Once each blue top tube is completely filled, gently invert the sample tube at least five times to ensure complete mixing of the contents.
  • Centrifuge specimens at >2500 x g for 10 minutes at room temperature.
  • Carefully remove plasma from cells using a plastic transfer pipette avoiding buffy coat.
  • Aliquot removed plasma into 2 plastic tubes containing a minimum of 1.0 mL of specimen in each tube.
  • Plasma samples must then be frozen at -20oC.
  • Once solidly frozen, they must be shipped on dry ice. Samples that have thawed in transit will be rejected.

Rejection Criteria

  • Common specimen rejected situations include: incorrect specimen type, insufficient volume, missing or incomplete specimen identifiers, incorrect specimen transport, or specimens outside stability limits. 
  • Specimens that have wrong ratio of blood to anticoagulant (fill volume), clotted or grossly hemolyzed.

Reference Values

 

Test

Age

Sex

Reference Range

N/A

N/A

N/A

N/A

Critical Values

Analyte

Unit

Low

High

Age

N/A

N/A

N/A

N/A

N/A

CPT Codes

85130 

LOINC Codes

74214-8

Volume

Preferred Volume: 2.0 mL

 

Minimum Volume: 1.0 mL

Specimen Stability

Storage Temperature

Stability

Room temperature

4 hours

Refrigerated

not acceptable

Frozen

30 days

Collection Instructions

  • Collect specimen per standard laboratory collection procedures. 
  • Once each blue top tube is completely filled, gently invert the sample tube at least five times to ensure complete mixing of the contents.
  • Blood sample should be ordinarily collected 3 to 4 hours following oral administration of apixaban, since this is the usual time required to reach peak plasma levels.

 

Turnaround Time

Turnaround times are relative to the time the specimen is received in the test laboratory. 

STAT Turnaround Time: N/A

 

Routine Turnaround Time: Up to 8 hours

 

Testing Schedule: 7 days a week from 8:00 am to 10:30 pm.

Clinical Indications

Monitoring of apixaban (Eliquis)

Methodology

Chromogenic by anti-Xa

Synonyms/Keyword Search

Eliquis; Anti-Xa

Additional Information

Peak plasma apixaban concentrations are typically reached approximately 3-4 hours following oral administration. Apixaban half-life is approximately 12 hours, assuming normal renal function.

 

No therapeutic ranges are provided by manufacturers of apixaban.  We must rely on pharmacokinetic assessment obtained from clinical trials as interim surrogates of “on-therapy ranges” (interval delineated by the 5th percentile trough and the 95th percentile peak plasma level).  If nonemergent DOAC testing is necessary, trough level assessment is recommended after at least four administrations.

 

Apixaban is monitored using an anti-Xa assay.

 

For 5mg BID apixaban

Trough range: 41-230 ng/mL (non-valvular Afib); 22-177 ng/mL (VTE treatment)

Peak range: 91-321 ng/mL (non-valvular Afib); 59-302 ng/mL (VTE treatment)

 

Actual target goals depend upon intended anticoagulation intensity and dosing schedules for the individual patient.

 

UCM Coagulation Lab cannot quantitate apixaban levels <15 ng/mL.

 

Anticoagulants measured by the anti-Xa assay (UFH, LMWH, fondaparinux, rivaroxaban, apixaban, edoxaban) cannot be resolved by that assay.  Therefore, if more than one of those agents is present in the plasma at once, the anti-Xa measurement will be the combined functional effect of all of their inhibitory activities.

 

Reference:

Gosselin RC et al. Thromb Haemost. 2018. 118(3):437-450

 

This test was validated by the University of Chicago Medicine Coagulation Laboratory. This test has not been cleared or approved by the FDA. The laboratory is regulated under CLIA as qualified to perform high-complexity testing.

 

All 3.2% sodium citrate light blue top tubes must have 9 to 1 ratio of blood to anticoagulant.

Last Review Date

08/18/2024