3 - 9 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
For more information, please view the literature below.
Blue-top (sodium citrate) tube
Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.1 Evacuated collection tubes must be filled to completion to ensure a proper blood to anticoagulant ratio.2,3 The sample should be mixed immediately by gentle inversion at least six times to ensure adequate mixing of the anticoagulant with the blood. A discard tube is not required prior to collection of coagulation samples.4,5 When noncitrate tubes are collected for other tests, collect sterile and nonadditive (red-top) tubes prior to citrate (blue-top) tubes. Any tube containing an alternate anticoagulant should be collected after the blue-top tube. Gel-barrier tubes and serum tubes with clot initiators should also be collected after the citrate tubes. Centrifuge and carefully remove the plasma using a plastic transfer pipette, being careful not to disturb the cells. Transfer the plasma into a LabCorp PP transpak frozen purple tube with screw cap (LabCorp N° 49482). Freeze immediately and maintain frozen until tested. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.
Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.
Freeze; five freeze/thaw cycles are acceptable. Stable at room temperature or refrigerated for four hours.
Do not draw from an arm with a heparin lock or heparinized catheter.
Assess thrombin formation and antithrombin consumption
Traumatic venipuncture, prolonged stasis, or inadequate centrifuging may invalidate results. Inadequate mixing of the patient sample and the citrate in the collection tube may result in falsely elevated levels. TAT levels may be elevated secondary to inflammation and microvascular thrombosis in surgical patients or those patients in acute distress.
TAT is measured by enzyme immunoassay using a sandwich technique. The patient sample containing TAT is incubated with antibodies against thrombin, and the unbound constituents are removed by washing. Enzyme conjugated antibodies to antithrombin are then added to the reaction, and the excess antibodies are removed by washing. The remaining (bound) enzymatic activity acts upon a chromophore and color development is proportional to the TAT in the sample.
Thrombin-antithrombin complexes (TAT) form covalently following thrombin generation and have a plasma half-life of 10 to 15 minutes. The presence of TAT indicates ongoing thrombin formation and the consumption of antithrombin. Upon activation of coagulation, antithrombin complexes with thrombin as well as other serine proteases. Complex formation is greatly enhanced by the presence of heparin or other glycosaminoglycans. The reaction initially is reversible, but becomes irreversible following the formation of a covalent bond between antithrombin and thrombin. This binding results in complete inhibition of thrombin's activity. Elevated levels of TAT may be associated with advancing age, pregnancy, septicemia, disseminated intravascular coagulation, multiple trauma, acute pancreatitis, acute and chronic leukemia, preëclampsia, acute and chronic liver disease, and other predisposing causes of thrombosis. Increased levels are also reported during heparin and fibrinolytic therapy. TAT levels are markedly reduced in the first 24 hours after receiving oral anticoagulants. The TAT assay can detect the intravascular generation of thrombin and provides valuable information in the diagnosis of thrombotic events. Decreasing TAT levels can also indicate the resolution of a thrombotic event. A normal TAT level in the presence of an elevated D-dimer may indicate an old thrombus. Elevated TAT measurements may be accompanied by increased levels of prothrombin fragment 1+2, fibrinopeptide A, fibrin(ogen) degradation products, and D-dimer. D-dimer has greater sensitivity for detection of deep venous thrombosis.
|Order Code||Order Code Name||Order Loinc||Result Code||Result Code Name||UofM||Result LOINC|
|500012||Thrombin Antithrombin Complex||500013||Thrombin Antithrombin Complex||ng/mL||14182-0|
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