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Background
Reptilase time is a particular coagulation test. This test will assess the formation of fibrin from fibrinogen present in plasma. Reptilase is an enzyme also called batroxobin. Thrombin time (TT) modified with reptilase time. Reptilase enzyme replaces thrombin. This enzyme is purified from the Bothrops atrox snake venom. Reptilase catalyzes fibrinopeptide A and not the fibrinopeptide B during the formation of a fibrin clot.
Reptilase time test is used to diagnose and differentiate specific coagulation diseases. Heparin does not inhibit reptilase. This test is used to assess an abnormally prolonged activated PTT (partial thromboplastin time) or PT (prothrombin time) along with an extended TT.
RT is important test which is used to distinguish between various causes of abnormal clotting. It plays a complementary role in the assessment of coagulation.
TT and reptilase time have been replaced with other tests, which are clotting based on functional fibrinogen to assess the fibrinogen.
Indications/Applications
Reptilase time test is indicated when there is an unexplained extent of PTT or PT along with TT.
Other clinical indications to perform reptilase time tests are like:
To diagnose afibrinogenemia or dysfibrinogenemia: RT test is used to check the suspected cases of afibrinogenemia where levels of fibrinogen is normal, but function of fibrinogen is impaired.
Acquired or congenital fibrinogen defects: RT is used to evaluate the acquired or congenital defects in fibrinogen like liver disease or DIC disseminated intravascular coagulation.
To monitor the heparin treatment: when a TT is prolonged because of the presence of heparin or other thrombin inhibitors, RT is used to check levels of fibrinogen and function.
Differences in coagulation tests: RT is used to identify heparin or fibrinogen factors which are contributing to abnormal findings in coagulation tests like extended TT or aPTT.
RT is used to differentiate between abnormalities in fibrinogen and inhibition of thrombin, to monitor the fibrinogen levels, and to assess the coagulation in liver disease.
To detect the fibrin degradation product
To investigate the extended TT
Reptilase time test may differentiate between contamination of heparin, any presence of fibrin degradation products, or dysfibrinogenemia.
Reference Range
The normal range of reptilase time is dependent on the instruments which are used in the laboratories.
Reptilase time (RT): 15 to 20 seconds
Healthy infants whose age is 6 months or below have a little extended reptiles time by 2 to 3 seconds.
Interpretation
Normal reptilase time: This indicates that there is normal conversion of fibrinogen to fibrin and does not have any fibrinogen abnormalities or any inhibitors.
Acquired and inherited hypofibrinogenemia: A reduced level of fibrinogen can lead to prolonged TT and RT. Inherited dysfibrinogenemia, myeloma, and liver disease can also lead to prolonged RT and TT. Hypoalbuminemia is condition with reduced levels of albumin, and it is linked to prolonged TT and RT.
Prolonged reptilase time: This indicates the fibrinogen abnormalities like:
Severe hypofibrinogenemia
Acquired or congenital afibrinogenemia
Acquired or congenital dysfibrinogenemia
Mild hyperfibrinogenaemia (more than 7 g/L)
Prolonged TT and normal RT: This indicates that there is a presence of heparin or direct thrombin inhibitors.
Prolonged RT and TT: This indicates that there is a presence of abnormalities in fibrinogen or presence of products which degrade fibrin.
Reptilase time test shows impaired formation of fibrin, which include:
DIC (Disseminated intravascular coagulation) – any presence of products which can degrade fibrin, D-dimer
Abnormal circulating protein because of multiple myeloma or amyloidosis
Heparin or direct antithrombin inhibitors like dabigatran, hirudin, argatroban, and bivalirudin cannot affect the sensitivity of this test.
Collection And Panels
Sample type: Citrated plasma
Sample collection: Blue top tube which contains 3.2 % sodium citrate
Centrifugation: Centrifuge the sample of about 2000 to 25 gm for 15 minutes to get the platelet-poor plasma
Sample storage: Store the sample for 8 hours at room temperature or sample which contain heparin for up to 2 hours. Plasma samples must be frozen in 1 to 2 hours of collecting. Samples are stable for 1 month at -20 º C and 6 to 9 months at -80 º C.
Panels:
Thrombin time (TT)
Prothrombin time (PTT)
Activated partial thromboplastin time (aPTT)
Modifying factors:
Low levels of albumin (less than 30 g/L) in the plasma samples may lead to extension of reptilase time because of the delay in polymerization of fibrin.
References
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