Reptilase Clotting Time

Reptilase is an enzyme derived from snake venom. It converts fibrinogen to fibrin by cleaving only fibrinopeptide A from the parent fibrinogen molecule. This is in contrast to thrombin, which cleaves both fibrinopeptides A and B.

The major value of the Reptilase Time in the clinical coagulation laboratory is that it is insensitive to the presence of heparin. Thus, a very prolonged (or non-clottable) Thrombin Time with a normal Reptilase Time most commonly indicates the presence of heparin. However, the presence of direct thrombin inhibitor drugs (lepirudin, argatroban or bivalirudin) give similar results.

The Reptilase Time is prolonged in the presence of low fibrinogen concentrations (typically <90 mg/ml), increased fibrin split products and by the presence of abnormal fibrinogen molecules (dysfibrinogenemia).

In the Hemostasis and Thrombosis Laboratory, the normal range for Reptilase Time is 14.9 - 19.3 seconds.