Thrombin Time



  • The thrombin time (TT) is not routinely performed as part of a coagulation screen.
      • Normal Range

      • <24 seconds
    • Important Lab Points

    • Performed by adding thrombin to a plasma sample.
    • Tests only the final step of fibrin clot formation.
    • If the TT is prolonged, a reptilase test is also performed to distinguish between causes.
  • Diluted thrombin time may have a role in the monitoring of factor IIa inhibitors (e.g. dabigatran).

Prolonged Thrombin Time

    • Interpretation

    • Prolonged reptilase - fibrinogen defects, fibrin degradation products
    • Normal reptilase - heparin, factor IIa inhibitors
    • Causes of Prolonged Thrombin Time

    • Fibrinogen defects - hypofibrinogenaemia, afibrogenaemia, dysfibrinogenaemia
    • Fibrin degradation products (e.g. in DIC)
    • Factor IIa inhibitors (e.g. dabigatran)
    • Heparin
Last updated on January 19th, 2018
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