The most commonly used test for clinical assessment of fibrinolytic activity is the Euglobulin Lysis Time (ELT). However the normal range is very wide, the long times are inconvenient and detection of inhibition is impossible. An attempt has been made to utilise the acceleration of the ELT when kaolin is present, to devise a test with shorter times, a narrower normal range, and better precision. The Euglobulin lysis time was carried out by a modification of the method of NILSSON and OLOW, after precipitation of the euglobulin in the absence of kaolin (ELT) and in the presence of 1 mg. kaolin/ml. plasma (KELT). In 14 control subjects the mean, SD, and range for the ELT were 168.6’, 54.6’, 84-290’; the corresponding values for the KELT were 60.3’, 8.3’ and 46-74’. However, it was found that there was no correlation between the ELT value and the corresponding KELT (’r’ = -0.021); on the contrary, the longer the ELT, the greater the shortening produced by kaolin and there is a direct correlation between the ELT and the shortening of the lysis time by kaolin; ’r’ = 0.988. It is concluded that the KELT has no value as a clinical measure of fibrinolytic activity; further, the results suggest that kaolin may remove an inhibitor(s) of plasminogen activation as well as initiating Factor XII - mediated plasminogen activation.
