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Test ID: Reptilase Test
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Reptilase Test
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Useful For
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Used to evaluate of a prolonged thrombin time (TT), It is mainly used to confirm or exclude the presence of heparin in the specimen .
Also to evaluate hypofibrinogenemia or dysfibrinogenemia in conjunction with the TT and fibrinogen assay
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Method name and description
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Coagulometric (Turbidimetric)
Test is performed using Sysmex CS5100 analyzer. Batroxobin (Reptilase), a purified enzyme from the snake Bothrops atrox. Batroxobin is added to citrated plasma and the time it takes for a clot to form is measured. The snake venoms are not inhibited by heparin and will give normal times for the clotting of normal plasma in the presence of heparin. The clotting times will, however, remain prolonged in the presence of raised FDP or reduced fibrinogen or abnormal fibrinogen or hypoalbuminemia.
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Clinical information
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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.
A normal Reptilase time in conjunction with a prolonged thrombin time suggests the presence of heparin in the sample. If both the batroxobin and thrombin time are prolonged, this may be due to the presence of fibrinogen degradation products or a quantitative or qualitative fibrinogen disorder.
| Thrombin Time |
Reptilase Time |
Cause |
Comments |
| Prolonged |
Equally prolonged |
Hypo- or afibrinogenemia |
Measure fibrinogen |
| Prolonged |
Markedly prolonged |
Dysfibrinogenemia |
Congenital or acquired (hepatoma) |
| Prolonged |
Normal |
Heparin |
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| Very prolonged |
Slightly prolonged |
Heparin with some hypo- or Dysfibrinogenemia |
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| Slightly prolonged |
Slightly prolonged |
?DIC |
Measure D-Dimer |
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Specimen type / Specimen volume / Specimen container
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Plasma Na Cit. Platelet-poor plasma.
Specimen Volume: 2.7 ml.
Container/Tube: Light-blue top (citrate).
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Collection instructions / Special Precautions / Timing of collection
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1- Sample collected in HMC facilities/others and transported to the lab within 1hour :
• Collect sample into light blue-top (sodium citrate).
• Tubes must be filled to within +/- 10% of their proper volume, to provide a 9:1 ratio of blood to citrate.
2- Samples collected in HMC facilities / others and which are expected not to reach the lab within 1hour:
• Centrifuge the whole blood and carefully remove the plasma by pipette not by decanting and send the plasma in a temperature-controlled environment (18-25ºC ) within one hour of centrifugation.
• If the transportation of the plasma can’t be within a maximum of 2hour , prepare platelet-poor plasma as follow:
A: Re-centrifuge plasma again.
B: Remove the top portion of plasma leaving approximately 250 mcL in the bottom to discard.
C: The double-centrifuged plasma should be aliquoted (0.5 to 1 mL per aliquot) into labeled plastic tubes. The number of tests ordered will determine the aliquots needed.
D: Freeze immediately at -20 ºC or below .
E: Specimens must arrive frozen.
3- Sample for Platelets function studies (Platelets function assay) , Citrated whole blood should reach HMC within a maximum of 1-2 hours of collection.
4- For heparin monitoring, follow the above mentioned steps.
5- Consider patient HCT %. , if HCT >55%, the volume of anticoagulant in the tube must be adjusted by the referring lab, as per the below table shows the volume of citrate (µL) to be removed from common sizes of coagulation specimen tubes prior to specimen collection. After removal of the specified volume of citrate, enough blood is added to fill the tube to the ideal volume.
| Hematocrit % |
Volume to be removed, µL |
| 2.7 ml Tube |
1.0 ml Tube |
| 56 |
50 |
20 |
| 57 |
50 |
20 |
| 58 |
60 |
20 |
| 59 |
60 |
20 |
| 60 |
70 |
30 |
| 61 |
70 |
30 |
| 62 |
80 |
30 |
| 63 |
80 |
30 |
| 64 |
90 |
30 |
| 65 |
90 |
30 |
| 66 |
100 |
40 |
| 67 |
100 |
40 |
| 68 |
110 |
40 |
| 69 |
110 |
40 |
| 70 |
120 |
40 |
| 71 |
120 |
40 |
| 72 |
130 |
50 |
| 73 |
130 |
50 |
| 74 |
140 |
50 |
| 75 |
140 |
50 |
| 76 |
150 |
50 |
| 77 |
150 |
60 |
| 78 |
160 |
60 |
| 79 |
160 |
60 |
| 80 |
170 |
60 |
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Relevant clinical information to be provided
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Patient/family history of bleeding disorder. History of anticoagulant therapy. History of chronic diseases
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Storage and transport instructions
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Specimen Rejection Criteria
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Specimens with no label or missing required identification
Broken, leaking or contaminated specimen
Clotted samples
Under-filled or overfilled sample tubes.
Wrong sample container sample received
Improper specimen transport temperature (e.g. like specimens which are needed to be sent on ice)
Old specimen (test-dependent)
Grossly Hemolyzed sample (test-dependent)
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Biological reference intervals and clinical decision values
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Reference range: 18.7 - 21.7 seconds.
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Factors affecting test performance and result interpretation
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No interference up to:
Triglycerides 200 mg/dL.
Hemoglobin 1000 mg/dL.
Bilirubin 60 mg/dL.
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Turnaround time / Days and times test performed / Specimen retention time
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STAT: 1hr.
Routine: 4 hrs/Daily/NA.
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