Reptilase and thrombin clotting time of plasma from patients treated with streptokinase.

Increasing clinical experience has gradually diminished the number of laboratory tests required for monitoring thrombolytic therapy. Still wider and wider use of plasminogen activators, often without a specialized laboratory basis, makes it imperative that some easily performed and reproducible tests should be at our disposal. Such conditions seem to be fulfilled by a simple assay of plasma clotting time. Usually thrombin was used as the clotting agent for this purpose. The test could not, however, be applied or would give erroneous results if heparin had been given simultaneously or following treatment with thrombolytic agents. The use of reptilase instead of thrombin is therefore proposed. In contrast to the observations made by some others, our previous studies (Latallo and Teisseyre, 1971) indicated that the addition of fibrinogen degradation products (FDP) to normal plasma resulted in parallel prolongation of both the thrombin and the reptilase clotting times. A comparison of both types of clotting tests was made on plasma samples from four patients obtained at various stages of treatment with Kabikinase (Kabi, Stockholm). Plasma was obtained from blood taken into a mixture of EACA and sodium citrate with the following assay system: 02 ml of plasma and 0O1 ml of enzyme, 370, pH = 7-8. Thrombin was dissolved in the same carrier solution as reptilase to a concentration which gave an identical clotting time of noimal plasma for both enzymes. Standardized preparation Reptilase R (Pentapharm, Basel) was used. Very good agreement was observed in values for clotting times produced by either enzyme. Both equally depend upon the concentration of fibrinogen and/or FDP. Comparison of clotting times of undiluted plasma samples and on samples mixed in a 1:1 ratio with normal plasma allowed workers to distinguish whether the observed prolongation was due to a very low content of fibrinogen or to a high concentration of fibrinogen degradation products.