Heparin Anti Xa Assay
Test Mnemonic
HEPASY
CPT Codes
- 85520 - QTY (1)
LOINC ®
3217-7
Aliases
- Factor Xa Inhibition/Heparin Assay
- Heparin Assay
Includes
- Heparin Anti Xa
Performing Laboratory
Cleveland Clinic Laboratories
Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 1 mL | Platelet-poor plasma | Sodium 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. | |
| 1.8 mL | Whole blood | Sodium citrate (Lt. Blue) | Ambient | 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. |
Stability
| Environmental Condition | Description |
|---|---|
| Ambient | Centrifuge within one hour of phlebotomy and test or freeze platelet poor plasma within four hours. |
| Frozen | 3 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) |
| Refrigerated | Unacceptable |
Days Performed
Sun - Sat
Turnaround Time
4 hours
Methodology
| Name | Description |
|---|---|
| Chromogenic |
Reference Range
| Heparin Anti Xa | |||||
|---|---|---|---|---|---|
| Sex | Age From | Age To | Type | Range | Range Unit |
| Years | 99 Years | Normal | Therapeutic range: 0.3 - 0.7 (standard nomogram) | IU/mL | Years | 99 Years | Normal | < 0.10 | IU/mL | Years | 99 Years | Normal | Stroke or low dose protocol: 0.2 - 0.5 (see EPIC for detailed nomogram) | IU/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 Heparin 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
For monitoring unfractionated heparin therapy. This assay may be useful in monitoring heparin therapy in individuals where the APTT cannot be used due to basal APTT elevation, such as those with a lupus anticoagulant.