LMW Anti Xa Assay




Test Mnemonic

LMWHEP

CPT Codes

  • 85520 - QTY (1)

LOINC ®

32684-3

Aliases

  • Low Molecular Weight Heparin Assay
  • Low Molecular Weight Heparin Assay Blood

Includes

  • LMW Anti Xa Assay

Performing Laboratory

Cleveland Clinic Laboratories


Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
1 mLPlatelet-poor plasmaSodium citrate (Lt. Blue) Centrifuge, aliquot and freeze ASAP.Collection tube must be filled to total fill volume. Inadequately filled tubes will be rejected. Non Testing Sites: Centrifuge within one hour of collection , aliquot platelet poor plasma into a separate tube with Epic Beaker label, freeze plasma at -20C, send frozen plasma to Main Campus on dry ice.
1.8Whole bloodSodium citrate (Lt. Blue)See noteCentrifuge, aliquot and freeze ASAP.Collection tube must be filled to total fill volume. Inadequately filled tubes will be rejected. Non Testing Sites: Centrifuge within one hour of collection , aliquot platelet poor plasma into a separate tube with Epic Beaker label, freeze plasma at -20C, send frozen plasma to Main Campus on dry ice.

Minimum Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
0.5 mL    A minimum of 0.5ml of platelet-poor plasma is needed; therefore, draw no less than 1.5ml whole blood in a 1.8ml sodium citrate tube.

Stability

Environmental Condition Description
AmbientCentrifuge within one hour of phlebotomy and test or freeze platelet poor plasma within four hours.
Frozen3 days at less than or equal to -18 degrees C (platelet poor plasma). 3 months at less than or equal to -74 degrees C (platelet poor plasma).
RefrigeratedUnacceptable

Days Performed

Sun - Sat

Turnaround Time

4 hours

Methodology

Name Description
Chromogenic 

Reference Range

LMW Anti Xa Assay
Sex Age From Age To Type Range Range Unit
   Years99 YearsNormal< 0.10IU/mL
   Years99 YearsNormalTherapeutic: 0.5 - 1.1IU/mL

Special Info

3.2% sodium citrate is the preferred anticoagulant recommended by CLSI. Patient samples should be centrifuged by the laboratory < 1 hour from collection time to prevent falsely decreased Low Molecular Weight Anti Xa values due to heparin neutralization by in vitro release of platelet factor 4. Samples that are centrifuged > 1 and < 4 hours from collection will have the following comment attached: Interpret with caution. Sample centrifuged greater than 1 hour from collection time. According to Clinical and Laboratory Standards Institute guidelines, results could be falsely decreased due to heparin neutralization by in vitro release of platelet factor 4. Suggest correlation with clinical findings and redraw if indicated.

Clinical Info

Used in monitoring patients on low molecular weight heparin.