Reptilase time

The reptilase time reagent is added directly to test plasma and the time to clot is recorded. It contains a fraction of the venom of the Lancehead snake (Bothrops atrox) which is a snake venom thrombin-like enzyme (SVTLE) that cleaves fibrinopeptide A but not fibrinopeptide B from fibrinogen to form fibrils of fibrin I. Heparin elevates APTT and thrombin time because it potentiates antithrombin but the reptile enzyme is unaffected by even a potentiated human inhibitor and will generate a normal clotting time in the presence of heparin. Abnormalities of fibrinogen will generate elevated reptilase times.
Clinical details: 
Blood samples taken from heparinised lines are occasionally contaminated with heparin and can falsely elevate APTT, thrombin time and even prothrombin time. To exclude heparin contamination, a reptilase time is performed because it is insensitive to heparin.
Reference range: 

0.94 - 1.06

Sample type and Volume required: 
External requests: Citrated platelet poor plasma
400µL x 1 aliquot
Internal requests: please refer to EPR label
Turnaround time: 
4 hours
Special sample instructions: 

The sample should be analysed within 4 hours of venepuncture. Please ensure sample tubes are filled exactly to the fill-line as underfilling creates a dilution error and leads to inaccurate results.

Diagnostic Haemostasis and Thrombosis Department
020 7188 2797
St Thomas' Hospital
North Wing - 4th and 5th Floors
Westminster Bridge Road
London SE1 7EH

Laboratory opening times
For clinical advice or interpretation of results, please contact the laboratory in the first instance.

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Last updated: 09/03/2017