Anti-XA, Low Molecular Weight Heparin

Message

Coagulation

Test Code

LAB316

Alias/See Also

Anti-XA (LMWH)
Low Molecular Weight Heparin

CPT Codes
85520

Preferred Specimen

2.7 ml. whole blood (blue top tube, citrate) TUBE MUST BE FULL
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

Do not place Blue top tube on ice

LAB: Centrifuge in validated Platelet Poor Plasma Centrifuges only

Transport Container

Processed Platelet Poor Plasma, preferably frozen

Transport Temperature

Processed Platelet Poor Plasma:
Room Temp – 4 hours
Refrigerated – 4 hours
Frozen – 1 month

Specimen Stability

Whole Blood: Ambient 1 hour
Plasma separated from whole blood 2-8°C 4 hours
Plasma separated from whole blood -20°C 1 month
Plasma separated from whole blood -70°C 6 months

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Underfilled tube - Quantity not Sufficient (QNS)
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

Limitations

Hemoglobin up to 300 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

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.