A new assay for the measurement of total progressive antithrombin

A new rapid method for assaying total antithrombin activity has been developed based on the inactivation of thrombin incorporated into an agarose gel, during the radial diffusion of plasma in the gel. The area of thrombin inactivation is subsequently observed by the coagulation of fibrinogen in a separate agarose gel layer poured over the thrombin gel. The method is described in detail and its accuracy assessed with respect to other antithrombin assays. Using specific antisera to alpha2-globulin (antithrombin III), alpha2-macroglobin and alpha1-antitrypsin, total antithrombin activity measured by this assay consisted of 47% alpha2-globulin, 29% alpha2-macroglobulin and 26% alpha1-antitrypsin.