blood 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.[citation needed]
Causes of prolonged thrombin time[3]
Reptilase time
Cause
Further 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
^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". American Journal of Clinical Pathology. 118 (2): 263–8. doi:10.1309/WUB3-72JT-E50M-EU8J. PMID 12162688.
^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.
^"Test ID: RTSC. Reptilase Time, Plasma". Mayo Clinic laboratories. Retrieved 2021-02-25.
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