Medicine:Reptilase time

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Short description: Laboratory blood test
Reptilase time
Medical diagnostics
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.[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

References

  1. "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. August 2002. doi:10.1309/WUB3-72JT-E50M-EU8J. PMID 12162688. 
  2. "Reptilase time in cirrhosis and hepatocellular carcinoma". Br Med J 2 (6091): 869–70. October 1977. doi:10.1136/bmj.2.6091.869-a. PMID 200301. 
  3. "Test ID: RTSC. Reptilase Time, Plasma". https://www.mayocliniclabs.com/test-catalog/Clinical+and+Interpretive/602185.