Glass activation-induced decrease or disappearance of normotest-thrombotest discrepancy in congenital coagulation disorders of the prothrombin complex.

Exposure of plasma to glass for 60 minutes will cause a sharp, progressive shortening of Thrombotest clotting times in all congenital disorders of the prothrombin complex. On the other hand Normotest clotting times will change only slightly or moderately after the same glass activation. Consequently the Normotest-Thrombotest percentile discrepancy, quite marked at zero time, became progressively smaller. This behaviour is similar to that observed in a group of coumarin treated patients. These studies indicate that the Normotest/Thrombotest discrepancy does not allow any differentiation to be made between congenital coagulation disorders and coumarin induced defect. This is consistent with the non-specificity of the phenomenon.