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Test Code 031 Thrombin Time

Additional Codes

MLAB: TT

PowerChart: Thrombin Clotting Time

Epic: LAB324 Thrombin Time

MA Cerner: Thrombin Time.

Test Method

Detection of Clot Formation; ACL Systems, Beckman Coulter, IL Test Thrombin (5)

Specimen Requirement

Sodium citrate blue-top tube filled to the area within the indicator arrow printed on the side of the tube.

Additional Specimen Collection Information

Invert the sodium citrate tube end to end 4 times to thoroughly mix blood and anticoagulant. The tube should be left stoppered until time of testing. Specimens stored at room temperature should be centrifuged and tested within four hours of specimen collection. If the testing is not completed within 24 hours the plasma should be removed from the cells and transferred to a plastic tube. Freeze the sample for up to two weeks. Frozen samples should be rapidly thawed at 37°C while gently mixed. Thawed samples should be centrifuged and tested immediately. If testing cannot be performed immediately the sample may be held for a maximum of 2 hours refrigerated, until tested.

  • Precautions:
    • It is not recommended to use a winged blood collection set (Butterfly).
    • If a vacuum tube butterfly must be used, the first tube in the series will be under-filled. Collect a “discard citrate tube”, and then collect the citrate tube used for testing. This will ensure the proper blood to anticoagulant ratio.
    • If using a syringe, use a BD Blood Transfer Device to transfer blood from the syringe to the citrate tube within one minute of collection. Hold the syringe with the plunger in the up-right position and allow the vacuum present to fill the tube. Before collection, be sure the syringe plunger is pushed to the top of the syringe. The transfer device may pop up and needs to be held down to completely fill tube to between fill lines.
    • Do not “force fill” blood into a vacuum tube. This may result in activation of the platelets possibly leading to erroneous results. Allow the vacuum present to fill the tube.
    • Do not remove vacuum tube cap to add blood.
    • Specimens should be obtained from a single venipuncture with minimal tissue trauma. Never combine multiple blood collections into a single vacuum tube.
    • Never re-use a syringe that was used for a pic line saline flush.

Refer to the "Citrated Plasma for Coagulation Studies" protocol in the Quality Assurance Manual.

Performance

Testing is performed Monday through Sunday.

Routine orders: Typically completed within 4 hours after the specimen arrives at the testing site.

STAT orders: Typically completed within 1 hour after the specimen arrives at the testing site.

Reference Values

10.3-16.6 Seconds

CPT Code Information

85670 Coagulopathy Testing: Thrombin Time, plasma

Useful For

The main utility of the thrombin time test is to detect or exclude the presence of heparin or heparin-like anticoagulants (which act by enhancing antithrombin's inhibition of thrombin and other procoagulant enzymes) when used in conjunction with the reptilase time (RT) in evaluating unexplained prolonged clotting times.

Identifying the cause of a prolonged prothrombin time, activated partial thromboplastin time, or dilute Russell's viper venom time when used in conjunction with the RT and fibrinogen assay.

LOINC Code Information

46717-5 Thrombin Time.Factor Substitution In Platelet Poor Plasma By Coagulation Assay-Immediately After Addition Of Bovine Thrombin