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Test ID RTSC Reptilase Time, Plasma

Specimen Required

Specimen Type: Platelet-poor plasma

Collection Container/Tube: Light-blue top (citrate)

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:

1. For complete instruction, see Coagulation Guidelines for Specimen Handling and Processing.

2. Centrifuge, remove plasma, and centrifuge plasma again.

3. Freeze plasma immediately (no longer than 4 hours after collection) at -20° C or, ideally below -40° C.

Additional Information:

1. Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.

2. Each coagulation assay requested should have its own vial.

Useful For

Evaluation of a prolonged thrombin time (TT): It is mainly used to confirm or exclude the presence of heparin in the specimen or specimen type


Evaluating hypofibrinogenemia or dysfibrinogenemia in conjunction with the TT and fibrinogen assay

Method Name

Optical Clot-Based

Reporting Name

Reptilase Time, P

Specimen Type

Plasma Na Cit

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma Na Cit Frozen 14 days

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject

Clinical Information

Prolonged clotting times may be associated with a wide variety of coagulation abnormalities including:

-Deficiency or functional abnormality (congenital or acquired) of any of the coagulation proteins

-Deficiency or functional abnormality of platelets

-Specific factor inhibitors

-Acute disseminated intravascular coagulation

-Exogenous anticoagulants (eg, heparin, warfarin)


The prothrombin time (PT) and activated partial thromboplastin time (APTT) are first-order tests for coagulation abnormalities and are prolonged in many bleeding disorders. A battery of coagulation tests is often required to determine the cause of prolonged clotting times. The thrombin time (TT) test is used to identify the cause of prolonged APTT or dilute Russell viper venom time (DRVVT). Reptilase time (RT) test is used to evaluate a prolonged TT.


Reptilase is a thrombin-like enzyme isolated from the venom of Bothrops atrox. Thrombin splits small fibrinopeptides A and B from fibrinogen molecules, producing fibrin monomer, which polymerizes to form a clot. Reptilase, however, splits off fibrinopeptide A but not B, which results in fibrin polymerization. In contrast to thrombin and the TT test which are inhibited by heparin, the RT is normal in the presence of heparin. Similar to the TT test, the RT is prolonged in the presence of hypofibrinogenemia and dysfibrinogenemia.

Reference Values

14.0-23.9 seconds


As seen in the following table, reptilase time can help distinguish among the various causes of a prolonged thrombin time (TT).


Thrombin Time

Reptilase Time





Hypo- or afibrinogenemia

Ascertain by determination of fibrinogen




Ascertain by specific assay



Heparin or inhibitor of thrombin

Differentiate by human TT and/or heparin assays



Fibrin(ogen) split products (FSP)

Ascertain by FSP or D-dimer assay



The reptilase time test has limited diagnostic value when ordered as a stand-alone test.

Clinical Reference

1. Greaves M, Preston FE: Approach to the bleeding patient. In Hemostasis and Thrombosis: Basic Principles and Clinical Practice. Fourth edition. Edited by RW Colman, J Hirsh, VJ Marder, et al: Philadelphia, JB Lippincott Company, 2001, pp 783-837

2. Funk C, Gmur J, Herold R, Straub PW: Reptilase-R: A new reagent in blood coagulation. Br J Haematol 1971 July;21(1):43-52

3. Latallo ZS, Teisseyre E: Evaluation of reptilase R and thrombin clotting time in the presence of fibrinogen degradation products and heparin. Scand J Haematol Suppl 1971;13:261-266

Method Description

The reptilase time assay is performed on the Instrumentation Laboratories ACL TOP. Patient plasma is combined with a reptilase reagent containing a thrombin-like enzyme triggering the coagulation process in the mixture. Time to clot formation is measured optically using a wavelength of 671 nm.(Owen CA, Bowie EJW, Thompson JH. Tests of hemostasis and blood coagulation. In: The Diagnosis of Bleeding Disorders. 2nd ed. Little, Brown and Company; 1975:85-154)

Day(s) Performed

Monday through Friday

Report Available

1 to 4 days

Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
RTSC Reptilase Time, P 6683-7


Result ID Test Result Name Result LOINC Value
RTSC Reptilase Time, P 6683-7


If not ordering electronically, complete, print, and send a Coagulation Test Request (T753) with the specimen.