Heparin Anti Xa Assay
Test Mnemonic
HEPASY
CPT Codes
- 85520 - QTY (1)
LOINC ®
3217-7
Aliases
- Factor Xa Inhibition/Heparin Assay
- Heparin Assay
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) | Frozen |
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 |
|---|---|
| Ambient | Centrifuge within one hour of phlebotomy and test or freeze platelet poor plasma within four hours. |
| Frozen | 2 weeks at less than or equal to -20 degrees C. 6 months at less than or equal to -70 degrees C. |
| 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.