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thrombin time (TT)

The assay is performed adding exogenous thrombin to citrated plasma & measuring the time to clot formation. Normal value: 1) time of control +/- 2 sec when control is 9-13 sec 2) time of control +/- 5 sec when control is 15-20 sec Clinical significance: - measures late phase of coagulation - affected by concentrations of fibrinogen & by the presence of fibrin degradation products - does NOT distinguish disseminated intravascular coagulation (DIC) from primary fibrinolysis Increases: 1) plasma fibrinogen levels < 50 mg/dL or dysfibrinogenemia* 2) presence of thrombin inhibitor a) heparin b) lepirudin c) argatroban 3) fibrin degradation products (DIC) 4) paraproteinemia 5) cirrhosis * may be associated with frequent or severe bleeding [3]

Related

coagulation cascade

Specific

thrombin time after addition of protamine sulfate

General

clinical coagulation test

References

  1. Clinical Diagnosis & Management by Laboratory Methods, 19th edition, J.B. Henry (ed), W.B. Saunders Co., Philadelphia, PA. 1996, pg 726
  2. Guide to Clinical Laboratory Tests, 3rd ed, NW Teitz (ed) WB Saunders, 1995
  3. Harrison's Principles of Internal Medicine, 13th ed. Isselbacher et al (eds), McGraw-Hill Inc. NY, 1994, pg 322
  4. Medical Knowledge Self Assessment Program (MKSAP) 16, 18. American College of Physicians, Philadelphia 2012, 2018.
  5. Panel of 12 tests Laboratory Test Directory ARUP: 30181
  6. Thrombin Time Laboratory Test Directory ARUP: 30260
  7. Panel of 16 tests Laboratory Test Directory ARUP: 30268
  8. Panel of 16 tests Laboratory Test Directory ARUP: 2003222

Component-of

coagulation screening panel DIC panel