A new chromogenic assay for the specific determination of prothrombin

A new method for the specific assay of prothrombin is described which utilises Taipan snake venom and the chromogenic substrate Tos-Gly-Pro-Arg-pNA (Chromozym TH). The method is sensitive and reproducible and shows good correlation with a conventional specific assay for prothrombin. The reaction is dependent on calcium ions and phospholipid, and is therefore sensitive to the coumarin-induced prothrombin defect. The assay is rapid and well suited for use in the routine coagulation laboratory.