Reptilase Time (RT)


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Subject: Reptilase Time (RT)

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  • RT measures the conversion of fibrinogen to fibrin when added to plasma. The reagent is a thrombin-like enzyme derived from venom of Bothrops atrox. It is unaffected by heparin or hirudin.

  • Normal value: <20 seconds.


  • An abnormal RT indicates an abnormality of fibrinogen, whereas a normal RT suggests heparin or hirudin as the cause of an abnormal thrombin time.

  • A RT evaluates prolonged PTT when heparin or hirudin contamination is suspected.

  • It also excludes dysfibrinogenemia.


Causes of Increased RT

  • Hypofibrinogenemia or dysfibrinogenemia

  • Slightly prolonged in the presence of fibrin degradation products as seen in severe DIC or pathologic fibrinolysis


  • Preanalytic: partially clotted blood or hemolyzed blood, improperly filled or stored test tubes, specimens collected in wrong tubes

  • Lipemic or icteric samples