Reptilase Time

Diagnosis of fibrinogen deficiency, both congenital and acquired, as well as screen for dysfibrinogenemia.6 Normal values for reptilase time when thrombin time is prolonged suggests the presence of heparin or a direct thrombin inhibitor.

This test is a qualitative assay of fibrinogen function and does not always indicate a specific disorder, thus additional testing may be required for clarification of prolongation in test results.

Reptilase is a thrombin-like enzyme. Unlike thrombin, which cleaves fibrinogen to produce fibrinopeptides A and B, reptilase cleaves the fibrinogen molecule to release only fibrinopeptide A.6,7 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.6,7 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. 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.6 Paraproteins and fibrin degradation products, especially fragments D and E, interfere in fibrin polymerization, thus prolonging both the thrombin time and reptilase time. Bovine thrombin inhibitors (antibovine thrombin antibody) may develop in patients 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.6 A prolonged thrombin time in a patient with a normal reptilase time suggest heparin therapy or contamination.

1. Adcock DM, Kressin DC, Marlar RA. Effect of 3.2% vs 3.8% sodium citrate concentration on routine coagulation testing. Am J Clin Pathol. 1997 Jan; 107(1):105-110. PubMed 8980376

2. Reneke J, Etzell J, Leslie S, Ng VL, Gottfried EL. Prolonged prothrombin time and activated partial thromboplastin time due to underfilled specimen tubes with 109 mmol/L (3.2%) citrate anticoagulant. Am J Clin Pathol. 1998 Jun; 109(6):754-757. PubMed 9620035

3. National Committee for Clinical Laboratory Standardization. Collection, Transport, and Processing of Blood Specimens for Coagulation Testing and General Performance of Coagulation Assays; Approved Guideline. 5th ed. Villanova, Pa: NCCLS; 2008. Document H21-A5:28(5).

4. Gottfried EL, Adachi MM. Prothrombin time and activated partial thromboplastin time can be performed on the first tube. Am J Clin Pathol. 1997 Jun; 107(6):681-683. PubMed 9169665

5. McGlasson DL, More L, Best HA, Norris WL, Doe RH, Ray H. Drawing specimens for coagulation testing: Is a second tube necessary? Clin Lab Sci. 1999 May-Jun; 12(3):137-139. PubMed 10539100

6. Adcock DM, Bethel MA, Macy PA. Coagulation Handbook.
Aurora, Colo: Esoterix−Colorado Coagulation; 2006.

7. Van Cott EM, Laposata M. Coagulation. In: Jacobs DS, Oxley DK, DeMott WR, eds. Laboratory Test Handbook With Key Word Index. 5th ed. Hudson, Ohio: Lexi-Comp Inc; 2001: 327-358.