A functional plasminogen assay utilizing the potentiating effect of fibrinogen to correct for the overestimation of plasminogen in pathological plasma samples.

An overestimation of the plasminogen concentration occurs in patients with elevated levels of fibrin degradation products (fdp) and/or fibrinogen, when using assays based on the activation of plasminogen by streptokinase (Sk) followed by the hydrolysis of a synthetic chromogenic substrate. This source of error could be overcome by addition of fibrinogen in excess to the plasminogen assay thereby obtaining maximum stimulation of the Sk-plasminogen complex. The late degradation products of fibrinogen and fibrin, Dcate and Ddimer, respectively, had no potentiating effect on the Sk-plasminogen complex. The modified assay was designed as a manual method or for a centrifugal analyzer. The excellent reproducibility is illustrated by the coefficient of variation (CV) within series being 1.3% (n = 24) and from day to day being 1.9% (n = 20).