Coagulation Inhibitors in Plasma and Serum
Heparin cofactor activity and antithrombin III (At-III) activity measured with amidolytic methods; antifactor Xa by a clotting method (Biggs et al., Brit. J. Haemat. 19, 287, 1970) and immunoassay of At-III (Fagerhol & Abildgaard, Scand. J. Haemat. 7, 10, 1970) in plasma and serum showed:1) There was a close correlation between the plasma values as measured by all these methods (r = 0.84–0.93).2) The difference between plasma and serum values (“consumption”) was lower in warfarin treated and in haemophiliacs than in the other groups.3) The difference between plasma and serum was greater when measured by the heparin cofactor activity method than by the other methods. The reason for this discrepancy will be discussed. The results in different patient groups will be reported.4) As the heparin cofactor activity assay can be completed within 10 minutes after blood sampling, and has a higher precision than clotting assay and immuno assay, it is preferable for clinical use.