[Estimation of Stuart factor using a synthetic substitute during oral anticoagulant treatment. Preliminary results...

The estimation of Stuart Factor (Factor X) with a new synthetic substrate S-2337, and the prothrombin time were compared in 91 patients treated with oral anticoagulants for more than one month. There was a good correlation between the two tests (r = 0.79 and 0.81 depending on the thromboplastin used). The results of out short study suggest a therapeutic zone between 20 p cent and 32 p cent of factor X but these values require confirmation. This method may constitute a progress in the laboratory supervision of treatment with coumarin derivatives for it permits better standardisation of the results and may easily be adapted to an autoanalyser.