A rapid screening test for reduced fibrinolytic activity of plasma: streptokinase activated lysis time

SUMMARY A simple screening method for determining the fibrinolytic activity of plasma is de-scribed. A streptokinase activated system is used, which measures the result of the interplay of all components of the fibrinolytic system with the exception of activators, which are added in excess. Mean lysis time and standard deviation with this method is 6-9 ± 1-4 min. The sensitivity of the method in detecting minor delays in clot lysis time is demonstrated. The methods available for the determination of reduced fibrinolytic activity of plasma are few and are not easily applied to individual cases owing to wide limits of normal. The dilute blood clot lysis time (Fearnley et al., 1957) has an arbitrary normal limit of 7 hours, but many normal clots lyse after 3-4 hours; for them 7 hours is an abnormal value. Similarly, the euglobulin lysis time (von Kaulla and Schultz, 1958) has a normal range of 2-5 to 4 hours, representing the lysis time of a clot with most inhibitors removed. In the fibrin plate method (Astrup and Mullertz, 1952) the area of lysis is measured, all the inherent inaccuracies of such measurements being increased by the small size of the area when lysis is delayed. Hick-man's (1971) method using labelled fibrinogen is accurate but rather cumbersome. The purpose of this paper is to describe a simple method for the determination of the fibrinolytic activity of plasma in an activated system. This method reflects the influence of all the components of the complex fibrinolytic system with the ex-ception of activators, which are added in excess. The method is based partly on the obser-vations of Konttinen (1965), who investigated the influence of various concentrations of streptokinase (SK) on plasma clot lysis time, and on the urokinase (UK) sensitivity test of McNicol et al. (1963)