| Primary Name | Antithrombin |
| Synonym | Antithrombin III |
| Synonym | Heparin cofactor activity |
| Contraction | AT |
| Contraction | AT III |
| Contraction | -- |
| UAB Procedure Number | 1000760 |
| CPT Code | 85300 |
| Specimen | Collect one (1) blue-stopper tube (3.2% sodium citrate), filled to specified volume. Specimen will be rejected if underfilled. |
| Specimen Management | Centrifuge blue-stopper tube within one (1) hour of collection, separate plasma and test or quick-freeze at -70°C. |
| Specimen Accepted | Daily including weekends |
| Test Performed | Monday-Friday *When the antithrombin test is ordered as part of a thrombosis risk profile, it is performed twice weekly. |
| Available Stat? | N0. |
| Description | When the functional AT level is consistently decreased, the patient may have a congenital deficiency. Chronic AT deficiency confers a 10- to 20-fold risk of venous thrombosis. Acquired AT deficiency occurs in prolonged heparin therapy, disseminated intravascular coagulation, surgery, preeclampsia, liver dysfunction, renal disease, and malignancies. Because the AT decreases with heparin therapy, wait 10 days after ending treatment to collect specimen. |
| Reference Interval | 78% - 126% |
| Follow-up Test | If the functional AT assay indicates a congenital deficiency, the antithrombin antigen assay may be used to distinguish qualitative from quantitative disorders. |
| Associated With | Venous thrombosis |
| Associated With | Disseminated intravascular coagulation |
| Associated With | Liver disease |
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