[Functional protein S in 77 patients treated with anticoagulants and in 32 probands with normal coagulation...

We determined functional protein S with a new automated clotting assay, total protein S antigen with the Laurell technique and free protein S antigen with an ELISA test and calculated the ratio of total protein S antigen and prothrombin antigen (Laurell) of plasmas of 77 patients oral anticoagulant therapy and of 32 normals. The correlation of total protein S antigen with protein S activity was found to be r = 0.857. The normal range of the tests was calculated for orally anticoagulated patients and for normals and was compared with the analytical data from 4 orally anticoagulated, congenital protein S deficiency patients. We believe that the automated functional protein S clotting assay is a quick and easily performed test, which now allows even for protein S the use of a functional assay as the first step for the screening of coagulation inhibitor deficiencies.