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Test Code HEP.ANTIXA HEPARIN ANTI-XA

Methodology

Chromogenic Assay

Useful For

Heparin Anti-Xa assay is Useful for measuring heparin concentration in patients treated with low-molecular-weight heparin preparations.  It is also useful when measuring heparin concentration in the presence of a prolonged baseline APTT (e.g., lupus anticoagulants). 

The anti-Xa assay is the preferred method for monitoring low-molecular-weight heparin (LMWH) therapy because of reduced sensitivity of the APTT assay

Specimen Requirements

Specimen Type:        Plasma

Container/Tube:        Light-blue top (3.2% buffered sodium citrate, with yellow-striped label)

Specimen Volume:    Full tube

Collection Instructions:

  1. Tube must be filled to capacity.
  2. Ratio of blood to anticoagulant is critical for valid coagulation results.
  3. Send whole blood in original tube.
  4. If specimen will arrive at Logan Health Medical Center Laboratory >1 hour after draw, process specimen as follows:
  • Spin for 10 minutes at 3,500 rpm (1,500 g).
  • Remove plasma from cells and place in a clean, plastic vial. 
  • Centrifuge again and transfer 1-mL plasma to a clean plastic vial.  Leave 0.5 mL plasma in the first aliquot tube to ensure the platelet pellet is not disturbed.
  • Freeze specimen.

Moderate or grossly hemolyzed specimens are not acceptable.

Day(s) Test Set Up

Monday through Sunday

Specimen Stability

Refrigerated

Reference Values

UFH Therapeutic Range: 

             All ages                                   0.30 - 0.70 IU/mL

 

LMWH Therapeutic Range:

            ≥ 18 years                               0.50 – 1.0 IU/mL for twice daily dosing

                                                1.0 - 2.0 IU/mL for once daily dosing

           

            ≥ 8 weeks to 17 years             0.50 - 1.0 IU/mL

                                                            0.10 – 0.30 IU/mL (prophylactic range)

 

            Reference ranges not established for patients less than 8 weeks old.

 

Performing Laboratory

Logan Health Medical Center Laboratory

Test Classification and CPT Coding

85520