Thrombin Time


Abbrev Code:TT   
Order Code:LAB324Order Name:Thrombin Time
Synonyms:TT
Methodology:Electromagnetic clot detection
CPT Codes: 85670 x1, 85670 x1
Turnaround Time:Within 8 hours if received into the testing laboratory by 2 p.m. Testing performed 5 days per week. If ordered with a  Lupus Anticoagulant panel, results will be reported when Lupus testing is complete. With pre-notification, STATs are done within 1 hour after receipt in the testing laboratory.
Associated Links:

Specimen Collection and Processing for Coagulation Specimens



Collection Instructions

Specimen:Blood
Optimal Volume:2.7 mL (in 3 mL tube) - filled to fill line on the tube.
Minimum\Peds Volume:1.8 mL (in 2 mL tube) - filled to fill line on the tube.
Container:Blue Na Citrate, 3.2% - fill to fill line on tube
Collection Instructions:See link to Specimen Collection and Processing for Coagulation Specimens.
Causes for Rejection:Underfilled tubes, overfilled tubes, clotted specimens, not received or processed and frozen within 4 hours of collection or, specimen thawed during transit.
Contraindications:Test is not sensitive for monitoring low molecular weight heparin.


Processing and Shipping

Specimen Processing:
  • Process for Platelet Poor Plasma within 4 hours of collection.
  • Aliquot plasma, place clear tape around label, and freeze at -20C or on dry ice within 4 hours of collection.
  • If multiple tests are collected on 1 blue top, split each blue top into 2 aliquots. Minimum 0.5 mL per tube.
  • A maximum of 6 aliquots are needed per collection.
     
See link to Specimen Collection and Processing for Coagulation Specimens.
Shipping Instructions:
  • Ensure specimen is frozen before shipping.
  • Ship on dry ice, sample must remain frozen during shipping.
     
See link to Specimen Collection and Processing for Coagulation Specimens.
Test Performed at or Referral Lab UM Special Coag (K)  (UMMC East Bank)


Interpretive

Reference Range:13-19 seconds
Limitations:This test is used as a screening test to determine if heparin is present in a sample when performing an inhibitor or mixing study.
Use:Thrombin time uses Human Thrombin, a Stago product containing titrated calcium thrombin approximately 1.5 NIH unit/mL, freeze-dried. This test is sensitive to very low concentrations of heparin.


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