Studies on assays for plasma prekallikrein and for the monitoring of coumarol therapy.

Chromogenic substrates were used to assay prekallikrein, prothrombin and factor X. Plasma prekallikrein was contact activated and allowed the splitting of HD-Pro-Phe-Arg-PNA which has affinity for plasma kallikrein. Prothrombin was assayed in various ways (immunologically, after activation with Ecarin or in a less specific way). Determination of factor X is considered as a possible specific method in the monitoring of coumarol therapy.