Antithrombin Activity, Plasma
Use
The test is useful for diagnosing antithrombin deficiency, whether acquired or congenital. It plays an important role in monitoring the treatment of antithrombin deficiency disorders, including the infusion of antithrombin therapeutic concentrate. Antithrombin deficiency can result in a thrombotic diathesis, making the patient susceptible to venous thromboembolisms such as deep vein thrombosis and pulmonary embolism. It can be due to inherited causes or acquired due to conditions such as liver disease, nephritic syndrome, or chemotherapy, and it has significant implications in heparin therapy resistance.
Special Instructions
Coagulation testing is complex and often requires multiple assays and correlation with clinical information. Consider ordering additional tests such as the Thrombophilia Profile, Plasma and Whole Blood. Double centrifugation of the specimen is critical to avoid platelet contamination which may lead to erroneous results. Each coagulation assay should have its own vial.
Limitations
The functional result of antithrombin is affected by heparin in concentrations greater than 4 U/mL, as well as by alpha-1-antitrypsin, alpha-2-macroglobulin, and heparin cofactor II in high amounts. Hemoglobin and bilirubin at high concentrations, and triglycerides above certain levels, can also impact the accuracy of the assay. Heparin therapy can lower plasma antithrombin activity temporarily, affecting results.
New York Approved
Methodology
Chromogenic Assay
Biomarkers
LOINC Codes
- 27811-9
- 27811-9
Result Turnaround Time
1-3 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
1 mL
Minimum Volume
0.5 mL
Container
Plastic vial
Collection Instructions
Centrifuge, transfer all plasma to a plastic vial, and centrifuge plasma again. Aliquot plasma into a plastic vial leaving 0.25 mL in the bottom of the centrifuged vial. Freeze plasma immediately at -20 degrees C or ideally at -40 degrees C or below.
Storage Instructions
Frozen at -20 degrees C for 14 days.
Causes for Rejection
Gross hemolysis, gross lipemia, gross icterus
Stability Requirements
| Temperature | Period |
|---|---|
| Frozen | 14 days |