We have investigated (Thrombosis Research 2012, in press.) the influence of each of the VKD factors on coagulation induced by dilute (trace amount) thromboplastin using rotational thromboelastometry (ROTEM). The dilute thromboplastin is by some scientists considered to reflect physiological clotting better than the 17,000 fold stronger thromboplastin used in the current PT assays. ROTEM measures coagulation in more detail than the traditional clotting times, i.e. initiation phase (clotting time), propagation phase (bulk clot formation) and stabilization phase. Taken together, these experiments using ROTEM show that the ROTEM clotting time (CT, initiation phase), ROTEM maximum velocity of clot formation (Max Vel, propagation phase) and the ROTEM MCF (stabilization phase) were affected much more by mildly and moderately low concentrations of factors II or X (at activity levels that are present during ideal anticoagulation) than by identical FVII or factor IX activity levels. Factors VII and IX mainly influenced the ROTEM parameters at very low concentrations (< 5%) which only occur during marked over anticoagulation. We conclude from these experiments that when coagulation is initiated with trace amount thromboplastin (physiological coagulation), reduction in concentration of coagulation factors II or X has much more effect on the development of a clot than do the concentrations of factors VII or IX except at extremely low activity levels of the latter two factors. Our experimental results may indicate that in patients anticoagulated with warfarin, the factor VII activity is a confounding source of variation in INR (PT) results. Hence, measuring the influence of factor II or X or both II and X simultaneously on fibrin formation might reduce INR fluctuation. Possibly, this could better predict the antithrombotic effect than the current tests do. Thus, measuring II or X or both simultaneously could possibly improve monitoring and dosing during VKA therapy. This has led to our invention of a new test, "Fiix-PT" (or Stuart-Prothrombin time) , which measures the combined action of factor II and factor X activity on clotting induced by tissue thromboplastin in PPP. We are not aware of any other scientists investigating this method and a local patent has been granted with international patent applications in process (March 2012). The Fiix-PT is not affected by reduced activity of any other coagulation factors. In comparison, the traditional test method (Quick PT or Owren´s PT) measures the combined effect of factors II, VII and X on fibrin formation in patients taking VKA.