Reptilase time may be more sensitive than a thrombin time to the presence of a dysfibrinogenemia. The reptilase clotting time may be used in place of, or in conjunction with, the thrombin time to measure fibrin formation.
Both reptilase time and thrombin time will be extended when functional fibrinogen levels are <100 mg/dL.
This can occur due to congenital conditions, including afibrinogenemia (complete lack of fibrinogen), hypofibrinogenemia, and in dysfibrinogenemia, a condition characterized by the presence of dysfunctional fibrinogen.
Bovine thrombin inhibitors (antibovine thrombin antibody) may develop in people previously treated with “fibrin glue” during surgical procedures (most fibrin glue products contain bovine thrombin). This acquired inhibitor prolongs the
(bovine-derived reagent) thrombin time, but does not prolong the reptilase time. A thrombin time using human-derived thrombin reagent will not be prolonged in the presence of a bovine thrombin inhibitor.
Unlike thrombin, reptilase is not affected by the presence of heparin, heparinoids, or hirudin and may be a useful tool in evaluating test plasma for their presence.
A prolonged thrombin time in a patient with a normal reptilase time suggest heparin therapy or contamination.
Acquired conditions that can lead to diminished fibrinogen levels and extended reptilase times include:
- liver disease,
- renal disease,
- disseminated intravascular coagulation (DIC),
- amyloidosis, malignancy, and thrombolytic therapy.
Paraproteins and fibrin degradation products, especially fragments D and E, interfere in fibrin polymerization, thus prolonging both the thrombin time and reptilase time.
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