Abstract: The invention is directed in part to a purified form of stabilized activated thrombin-activatable fibrinolysis inhibitor (TAFIa). The invention is further directed to a method of producing stabilized TAFIa. The invention is also directed to methods for therapeutic use of stabilized TAFIa such as in the treatment, prevention or management of diseases via an anti-coagulant effect. The invention is also directed to methods for therapeutic use of inhibitors of TAFIa such as in the treatment, prevention or management of diseases via a procoagulant effect. The invention is also directed to methods of diagnostic use of stabilized TAFIa such as a standard in a chromogenic or a fluorometric carboxypeptidase activity assay. The present invention is also directed to kits comprising stabilized TAFIa useful in measuring carboxypepetidase activity.