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Heparin Anti Xa Fondaparinux (Arixtra)

Mnemonic:    [Unlist Lab]
Name:    Heparin Anti Xa Fondaparinux (Arixtra)
Specimen:    1 mL plasma from a FULL sodium citrate Blue top tube. Allow tube to fill to proper capacity. Mix immediately by gentle inversion 4 times. Blue top must be double spun and the plasma frozen immediately.

Prophylactic range is based on a collection time 3 hours post dose.
Minimum Spec:    0.5 Ml
Transport Temp:    FREEZE
Ref Lab/Code:    EMMC (ALI)
  Method:    Chromogenic
Note:    When administered at the recommended doses, routine coagulation tests such as Prothrombin Time (PT/INR) and Activated Partial Thromboplastin Time (aPTT) are relatively insensitive measures of ARIXTRA activity, and are therefore unsuitable for monitoring.

The anti-Factor Xa activiity of fondaparinux sodium can be measured by anti-Xa assay using the appropriate calibrator (fondaparinux). Since the international standards of heparin or LMWH are not appropriate calibrators, the activity of fondaprinux sodium is expressed in milligrams (mgs( of the fondaparinux and cannot be compared with activities of heparin or low molecular weight heparin.