Ecarin clotting time

Ecarin clotting time
Saw-scaled viper, Echis carinatus
Purpose	used to monitor anticoagulation during treatment with hirudin

Ecarin clotting time (ECT) is a laboratory test used to monitor anticoagulation during treatment with hirudin, an anticoagulant medication which was originally isolated from leech saliva. Ecarin, the primary reagent in this assay, is derived from the venom of the saw-scaled viper, Echis carinatus.^{[citation needed]}

In the clinical assay, a known quantity of ecarin is added to the plasma of a patient treated with hirudin. Ecarin activates prothrombin through a specific proteolytic cleavage, which produces meizothrombin, a prothrombin-thrombin intermediate which retains the full molecular weight of prothrombin, but possesses a low level of procoagulant enzymatic activity. Crucially, this activity is inhibited by hirudin and other direct thrombin inhibitors, but not by heparin. The ECT is also unaffected by prior treatment with warfarin or the presence of phospholipid-dependent anticoagulants, such as lupus anticoagulant. Thus, the ECT is prolonged in a specific and linear fashion with increasing concentrations of hirudin. An enhancement of the ECT is the ecarin chromogenic assay (ECA) in which diluted sample is mixed with an excess of purified prothrombin and the generated meizothrombin is measured with a specific chromogenic substrate. This assay shows no interference from prothrombin or fibrinogen in the sample and is suitable for the measurement of all direct thrombin inhibitors.^[1]^[2]^[3]^[4]

References

^ Nowak G (2003). "The ecarin clotting time, a universal method to quantify direct thrombin inhibitors". Pathophysiol. Haemost. Thromb. 33 (4): 173–83. doi:10.1159/000081505. PMID 15583446.
^ Fabrizio MC. 2001. Use of Ecarin Clotting Time (ECT) with Lepirudin Therapy in Heparin-Induced Thrombocytopenia and Cardiopulmonary Bypass. JECT 33:117–125. PDF Archived 2007-09-27 at the Wayback Machine at Journal of The American Society of ExtraCorporeal Technology. Accessed 5 June 2007.
^ Textarin/Ecarin Time at Specialty Laboratories. Accessed 5 June 2007.
^ Lange U, Nowak G, Bucha E. Ecarin chromogenic assay—a new method for quantitative determination of direct thrombin inhibitors like hirudin. Pathophysiol Haemost Thromb. 2003 Jul-2004 Aug;33(4):184-91.

v t e Hematology blood tests
Complete blood count	Hemoglobin Hematocrit Red blood cell count Red blood cell indices Mean corpuscular hemoglobin Mean corpuscular hemoglobin concentration Mean corpuscular volume Red blood cell distribution width White blood cell count White blood cell differential Absolute neutrophil count Platelet count Mean platelet volume Reticulocyte count Reticulocyte index
Other tests of red blood cells	Blood volume Total blood volume (TBV) Plasma volume (PV) Red cell volume (RCV) Fetal hemoglobin Apt–Downey test Kleihauer–Betke test Hemoglobinopathy testing Hemoglobin electrophoresis Sickle solubility test Mentzer index Erythrocyte sedimentation rate Haptoglobin Monocyte distribution width (MDW) Osmotic fragility
Coagulation	Clotting factors Prothrombin time Partial thromboplastin time Thrombin time Activated clotting time Fibrinogen Bleeding time animal enzyme Reptilase time Ecarin clotting time Dilute Russell's viper venom time Thrombin generation assay Calibrated automated thrombogram ST Genesia-based test Thromboelastography Thrombodynamics test Overall hemostatic potential Coagulation activation markers Prothrombin fragments 1+2 Thrombin–antithrombin complex Fibrinopeptide A Fibrin monomers Activated protein C–protein C inhibitor Fibrinolysis Euglobulin lysis time D-Dimer Plasmin-α₂-antiplasmin complex Von Willebrand factor Ristocetin-induced platelet aggregation Activated protein C resistance test aPTT-based activated protein C resistance test ETP-based activated protein C resistance test
Other	Blood film Blood viscosity Nitro blue tetrazolium chloride test Flow cytometry Immunophenotyping

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