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Anti-XA, Low Molecular Weight Heparin
MessageCoagulation
Test Code
LAB316
Alias/See Also
Anti-XA (LMWH) Low Molecular Weight Heparin, LMW
CPT Codes
85520
Preferred Specimen
Blue top 3.2% citrated tube, plasma
Note: Do not place Blue top tube on ice
Note: Do not place Blue top tube on ice
Minimum Volume
2.7 mL whole blood filled to the designated line on specimen container (blue top tube, citrate)
Other Acceptable Specimens
1.8mL Low Volume blue top tube, citrated
Instructions
LAB: Centrifuge in validated Platelet Poor Plasma Centrifuge for 2 minutes at 7200 rpm. Specimen to be delivered to Coagulation department STAT. Notify CLS upon arrival.
**Testing must be completed within 4 hours of collection.
Note: If unable to deliver whole blood to testing laboratory within stability time, platelet poor plasma should be aliquoted and placed in freezer. Centrifuge light blue-top for 2 minutes at 7200 rpm (STAT Coag centrifuge) within 60 minutes of collection. Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet buffy layer and place into a plastic vial. Centrifuge aliquoted plasma a second time and transfer platelet-poor plasma into a new plastic vial and place in 2 – 8℃ refrigerator or freeze -20℃ if delay longer than 1 hour. Once thawed, specimen must be tested within 2 hours.
Freeze aliquot at -20℃ for at least 1 hour when sending to alternate campus for testing.
**Testing must be completed within 4 hours of collection.
Note: If unable to deliver whole blood to testing laboratory within stability time, platelet poor plasma should be aliquoted and placed in freezer. Centrifuge light blue-top for 2 minutes at 7200 rpm (STAT Coag centrifuge) within 60 minutes of collection. Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet buffy layer and place into a plastic vial. Centrifuge aliquoted plasma a second time and transfer platelet-poor plasma into a new plastic vial and place in 2 – 8℃ refrigerator or freeze -20℃ if delay longer than 1 hour. Once thawed, specimen must be tested within 2 hours.
Freeze aliquot at -20℃ for at least 1 hour when sending to alternate campus for testing.
Transport Temperature
Ambient: whole blood 1 hour
Frozen (-20℃): plasma frozen for at least 1 – 2 hours
Frozen (-20℃): plasma frozen for at least 1 – 2 hours
Specimen Stability
Whole Blood: Ambient 1 hour
Processed Platelet Poor Plasma:
Processed Platelet Poor Plasma:
| Room Temp (15-25° C) | 4 hours |
| Refrigerated (2-8°C) | 4 hours |
| Frozen (-20°C) | 1 month |
| Frozen (-70°C or colder) | 6 months |
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Underfilled tube - Quantity not Sufficient (QNS)
Clotted specimen
Clotted specimen
Methodology
Heparin is analyzed as a complex with antithrombin present in the sample. The concentration of this complex is dependent on the availability of the patient's endogenous antithrombin. When the heparin - antithrombin complex is formed, two competing reactions take place: Factor Xa is neutralized by the heparin-antithrombin complex Residual Factor Xa is quantified with a synthetic chromogenic substrate. The paranitroaniline released is monitored kinetically at 405 nm and is inversely proportional to the heparin level in the sample. In order to reduce the influence from heparin antagonists, such as platelet factor 4 (PF4), dextran sulfate is included in the reaction mixture
FDA Status
Cleared
Report Available
STAT: 1 hour
Routine: Same Day
Routine: Same Day
Limitations
Hemoglobin up to 300 mg/dL
Bilirubin up to 20 mg/dL
Triglyceride up to 800 mg/dL.
Bilirubin up to 20 mg/dL
Triglyceride up to 800 mg/dL.
Reference Range
0.5 - 1.1 U/mL
Clinical Significance
To measure biological activity of Heparin as antithrombotic drug.
Performing Laboratory
Hoag Hospital Irvine / Hoag Hospital Newport
