Reptilase time

Reptilase time
Purposeblood test used to detect deficiency or abnormalities in fibrinogen

Reptilase time (RT) is a blood test used to detect deficiency or abnormalities in fibrinogen,[1][2] especially in cases of heparin contamination.

Reptilase, an enzyme found in the venom of Bothrops snakes, has activity similar to thrombin. Unlike thrombin, reptilase is resistant to inhibition by antithrombin III. Thus, the reptilase time is not prolonged in blood samples containing heparin, hirudin, or direct thrombin inhibitors, whereas the thrombin time will be prolonged in these samples. Reptilase also differs from thrombin by releasing fibrinopeptide A, but not fibrinopeptide B, in its cleavage of fibrinogen.

Causes of prolonged thrombin time[3]
Reptilase timeCauseFurther workup indicated
Normal Heparin, hirudin, or direct thrombin inhibitor Human TT and/or heparin assays
Prolonged Hypo- or afibrinogenemia Fibrinogen quantification
Dysfibrinogenemia Fibrinogen activity assay
Fibrin(ogen) split products (FSP) FSP or D-dimer quantification

References

  1. ↑ Van Cott EM, Smith EY, Galanakis DK (August 2002). "Elevated fibrinogen in an acute phase reaction prolongs the reptilase time but typically not the thrombin time". Am. J. Clin. Pathol. 118 (2): 263–8. doi:10.1309/WUB3-72JT-E50M-EU8J. PMID 12162688.
  2. ↑ Johnson PJ, White Y, Woolf IL, Williams R (October 1977). "Reptilase time in cirrhosis and hepatocellular carcinoma". Br Med J. 2 (6091): 869–70. doi:10.1136/bmj.2.6091.869-a. PMC 1631704. PMID 200301.
  3. ↑ "Test ID: RTSC. Reptilase Time, Plasma". Mayo Clinic laboratories. Retrieved 2021-02-25.


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