Antithrombin - plasma
Last updated: Monday, 06, August, 2007
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| Item | Process |
|---|---|
| Specimen | 4.5 mL blood added to 0.5 mL citrate. |
| Method | Functional assay followed by immunoassay if abnormal. |
| Reference Interval | Method dependent - consult pathologist. Functional (guide only): 80-120% of activity in pooled normal plasma Immunoassay: 0.2-0.4 g/L. |
| Application | Investigation of venous thromboembolism; recurrent, unexplained or with positive family history. The test should not be performed whilst the patient is receiving heparin, as levels will be reduced. Immunoassay is not appropriate for initial testing. |
| Interpretation | Antithrombin is a major natural inhibitor of activated coagulation factors; antithrombin deficiency is associated with an increased risk of venous thromboembolism. Deficiency may be inherited or acquired (eg, liver disease, oestrogen therapy, nephrotic syndrome). |