Effect of streptokinase on fibrinogen and related proteins in plasma

We investigated the effect of streptokinase on determination of fibrinogen and related clottable proteins in an effort to assess the relative reliability of these determinations in monitoring patients being treated with streptokinase. Citrated plasma was incubated with and without streptokinase, then assayed for fibrinogen (I), fibrin(ogen) degradation products (II), total clottable protein (III), and plasminogen (IV). Values for I decreased rapidly. Values for III and IV generally paralleled those for I, values for III lacked adequate sensitivity. II, low initially, increased to 80 mg/L in 1-2 h. Soybean trypsin inhibitor effectively stabilized all these constituents (except IV) in streptokinase-treated plasma, and we recommend that this (or some other such) inhibitor of fibrinolysis be used routinely when specimens are collected for these determinations. Data are presented that suggest that transient polymers are formed, the clinical significance of which is not known.