Test ID: RPTL
Reptilase Time, Plasma
Useful For 
Suggests clinical disorders or settings where the test may be helpful
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
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
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's 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 Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
14-23 seconds
Interpretation Provides information to assist in interpretation of the test results
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 | Causes | Remarks |
| Prolonged | Prolonged | Hypo- or afibrinogenemia | Ascertain by determination of fibrinogen |
| Prolonged | Prolonged | Dysfibrinogenemia | Ascertain by specific assay |
| Prolonged | Normal | Heparin or inhibitor of thrombin | Differentiate by human TT and/or heparin assays |
| Prolonged | Prolonged | Fibrin(ogen) split products (FSP) | Ascertain by FSP or D-dimer assay |
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
The reptilase time test has limited diagnostic value when ordered as a stand-alone test.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
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
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