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Test Code:
TT

Order Name:
Thrombin Time (TT)*

 
Useful For:
Detecting or excluding the presence of heparin or heparin-like anticoagulants.

Identifying the cause of a prolonged prothrombin time, activated partial thromboplastin time, or dilute Russell viper venom time when used in conjunction with the RT and fibrinogen assay
 
Methodology:
Clotting assay
 
 
 
Test Code:
TT

Order Name:
Thrombin Time (TT)*

 
Collection Specimen Or Container:
Blood/ Sodium citrate tube (Sodium Citrate 3.2% anticoagulant, Blue top) 3 mL, 1 tube
 
Specimen Testing Type:
Citrate plasma, minimum volume 0.5 mL
 
Sub Mission Container:
Plastic tube
 
Rejection Criteria:
Hemolysis: Hemoglobin >500 mg/dL
Lipemia: The presence of lipemia is unacceptable with this assay.
Icterus: Bilirubin >24 mg/dL
Other: Clotted specimen will be rejected.
 
Specimen Stabillity:
Specimen type Temperature Time
Whole blood, Sodium citrate Room temperature, 18oC to 25oC 4 hours
Plasma, Sodium citrate Room temperature, 18oC to 25oC 4 hours
Refrigerated, 2oC to 8oC 4 hours
Frozen, -20oC 2 weeks
Frozen, -70oC 1 year
 
 
 
Test Code:
TT

Order Name:
Thrombin Time (TT)*

 
Method detail:
Clotting assay
 
Schedule:
Tested Daily (24 hours)
 
Turnaround Time:
Collected specimen to report within 90 mins.
 
Performing Location:
Hematology, Laboratory Department Tel. 17255
 
Specimen Retention Time:
14 days
 
 
 
Test Code:
TT

Order Name:
Thrombin Time (TT)*

 
 
Clinical Information:
The prothrombin time and activated partial thromboplastin time are first-order tests for coagulation abnormalities and are prolonged in many disorders. A battery of coagulation tests is often required to determine the cause of prolonged clotting times.

 Thrombin catalyzes the transformation of fibrinogen to fibrin (by cleaving fibrinpeptides A and B), which is followed by polymerization of fibrin to form a clot. The thrombin time (TT) test measures the time of clot formation when thrombin is added to citrated plasma. The phospholipid-dependent procoagulant enzyme cascades (intrinsic, extrinsic, and "common" pathway) are bypassed by the addition of exogenous thrombin. Therefore, the TT mainly reflects functions and interactions of solution-phase exogenous thrombin and endogenous fibrinogen.
 
Reference Value:
12.60 - 16.30 Second
Note: The reference range will change by reagent lot.
 
Interpretation:
Prolongation of the thrombin time (TT) is consistent with the presence of heparin-like anticoagulants, hypofibrinogenemia, dysfibrinogenemia, fibrin degradation products, and antibody inhibitors of thrombin. An immeasurably prolonged TT is usually the result of heparin in the specimen or, rarely, the presence of thrombin antibodies or afibrinogenemia.
 
When the TT test is performed with diluted bovine thrombin to achieve a normal plasma clotting time of about 20 seconds, the TT is capable of detecting unfractionated heparin at a concentration of 0.05 units/mL of heparin.
 
Other tests useful in interpreting the significance of prolongation of the TT include: reptilase time (RT), human thrombin time, clottable fibrinogen assay, and the fibrin D-dimer assay. These tests are available as components of coagulation profile test panels. As seen in the following table, RT can help distinguish among the various causes of a prolonged TT.
 
Clinical Reference:
  1. Manufacturer’s reagent package insert Thrombin Time, HemosIL™, Instrumentation Laboratory Company - Bedford, MA 01730-2443 (USA),Instrumentation Laboratory SpA - V.le Monza 338 - 20128 Milano (Italy) ; 12/2016
  2. https://www.mayocliniclabs.com (Retrieved: 22 Jan 2019)