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Test Code HEPXA Heparin Anti-Xa Assay, Plasma



Performing Laboratory

Aspen Valley Hospital

Physician Office Specimen Requirements

Container/Tube:  Light blue-top (sodium citrate) tube(s)

Specimen:  1 mL of sodium citrate plasma

Transport Temperature:  Ambient

Collection Instructions:  If there is a delay in transport of >4 hours, spin down and send 1 mL of platelet-poor plasma frozen in plastic vial.

Reference Values

Unfractionated heparin:  0.32-0.67 IU/mL


The therapeutic range is specific for each low molecular weight heparin.

Enoxaparin (LOVENOX®): 

0.60-1.00 IU/mL (twice-daily dose)

1.00-2.00 IU/mL (once-daily dose)

Dalteparin (Fragmin):  1.05 IU/mL (target)


Reference: CHEST 2004, Sept;126(3):188S-203S

Day(s) Test Set Up

Monday through Sunday

Test Classification and CPT Coding