Heparin Anti-Xa
Also known as: Heparin Assay
Use
Determine the plasma level of unfractionated heparin (UFH) or low molecular weight heparin (LMWH)
Special Instructions
If the patient's hematocrit exceeds 55%, adjust the citrate volume in the collection tube. Draw Heparin anti-Xa levels six hours after initiation or dosage changes of unfractionated heparin or low molecular weight heparin, depending on the frequency of administration. Monitoring using Fondaparinux Anti-Xa [500465] should occur three hours postadministration for therapeutic monitoring of fondaparinux.
Limitations
The heparin anti-Xa assay may be more appropriate for monitoring heparin therapy than aPTT in cases involving factors that affect heparin bioavailability or alter the aPTT dose response such as aging, obesity, or hepatic disease. These factors might extend the aPTT baseline, making the anti-Xa assay a more suitable alternative for certain patients. The aPTT is not recommended for therapeutic monitoring of low molecular weight heparin.
Methodology
Other
Biomarkers
LOINC Codes
- 3274-8
- 3274-8
Result Turnaround Time
1-3 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
1 mL
Minimum Volume
Not provided
Container
Blue-top (sodium citrate) tube
Collection Instructions
Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate. Ensure the tube is filled to completion to maintain the correct blood to anticoagulant ratio, mix immediately by gentle inversion, and transfer plasma to a Labcorp PP transpak frozen purple tube. Freeze immediately.
Storage Instructions
Freeze.
Causes for Rejection
Gross hemolysis; clotted specimen; frozen specimen thawed in transit; improper labeling