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: 

0.95 - 1.07

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
St Thomas': 020 7188 2797; Guy's: 020 7188 7188 ext. 53860
St Thomas' Hospital
North Wing - 4th and 5th Floors
Westminster Bridge Road
London SE1 7EH

Laboratory opening times

Guy's Hospital
Southwark Wing - 4th Floor
Great Maze Pond
London SE1 9RT

Outside core hours, contact Duty Haemostasis Biomedical Scientist
For clinical advice or interpretation of results, please contact the laboratory in the first instance.

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Last updated: 03/10/2022