Antithrombin III Activity with Reflex to Antithrombin III Antigen
Also known as: AT3, Heparin Cofactor, AT III
Use
This test measures the activity of Antithrombin III in blood plasma. Antithrombin III is a protein in the blood that helps regulate blood clotting. It is important for diagnosing conditions related to abnormal blood clotting, such as inherited antithrombin deficiency, which can lead to thromboembolism and other clotting disorders.
Special Instructions
If Antithrombin III activity is low, an additional antigen test is performed to help determine if the deficiency is due to a lack of protein or dysfunctional protein.
Limitations
The test may not accurately assess antithrombin activity in patients on heparin therapy, as heparin can interact with antithrombin and affect its activity. Certain medications and acute-phase inflammatory responses can also interfere with test results.
Methodology
Immunoassay (ELISA)
Biomarkers
Result Turnaround Time
2-4 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
3 mL
Minimum Volume
1 mL
Container
Citrate (light blue-top) tube
Collection Instructions
Collect plasma in a light blue-top tube containing sodium citrate. Ensure proper blood-to-anticoagulant ratio.
Storage Instructions
Keep refrigerated until testing.
Causes for Rejection
Hemolysis, improper tube type, clotted sample.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 8 hours |
| Refrigerated | 48 hours |
| Frozen | 2 weeks |