The extrinsic coagulation activity assay.
A chromogenic assay for the tissue factor-mediated thrombin generation was developed, the extrinsic coagulation activity assay: 50 microL citrated plasma is incubated with 5 microL tissue factor in 6% albumin and 250 mM CaCl2. After 1-minute (37 degrees C) coagulation reaction time, (extrinsic coagulation activity assay with 1-minute coagulation reaction time; generating normally about 1 IU/mL thrombin) 100 microL 2.5 M arginine is added to stop hemostasis activation. Generated thrombin is then chromogenically quantified. The normal extrinsic coagulation activity assay range is 100% +/- 20%. Extrinsic coagulation activity assay in plasma of patients on heparin or coumarines is about 10-fold lower. Advantages of extrinsic coagulation activity assay: normal range of extrinsic hemostasis is truly represented, patients prone to hyper-activated extrinsic pathway are detected, anticoagulants result in respective test inhibition, fibrinogen/fibrin concentration does not artefactually alters the test result, plasma matrix is not changed significantly in the assay, and assay results are IU/mL thrombin or % of normal, which can be measured by every normal photometer.
Stief
Thomas W
TW
Department of Clinical Chemistry, Central Laboratory, University Hospital, Marburg, Germany. thstief@med.uni
Wieczerzak
Aleksandra
A
Renz
Harald
H
D001120:Arginine; D001780:Blood Coagulation Tests / Q000379:methods* / Q000592:standards; D001793:Blood Preservation; D002863:Chromogenic Compounds; D006801:Humans; D009391:Nephelometry and Turbidimetry; D011517:Prothrombin Time; D012016:Reference Values; D013696:Temperature; D013917:Thrombin / Q000032:analysis / Q000096:biosynthesis; D013925:Thromboplastin / Q000494:pharmacology
D002863:Chromogenic Compounds; D013925:Thromboplastin; D001120:Arginine; D013917:Thrombin