title: Radioimmunoassays for protein C and factor X. Plasma antigen levels in abnormal hemostatic states.
abstract: Specific radioimmunoassays, sensitive to plasma levels of less than 1% of normal, were developed for protein C and Factor X. In 31 normal subjects, mean plasma antigen levels were as follows: protein C, 3.23 +/- 0.79 microgram/mL (2 SD); Factor X, 7.74 +/- 1.81 microgram/mL. In patient son chronic warfarin therapy, protein C and factor X were depressed equivalently: protein C, 42% +/- 20% (of a pooled plasma reference); Factor X, 44% +/- 24%. Protein C antigen fell much more rapidly than Factor X antigen when warfarin therapy was begun, creating an initial period of potential hypercoagulability. In patients with severe liver disease, mean protein C antigen (25% +/- 17%) was lower than Factor X antigen (51% +/- 29%). Protein C antigen levels did not appear to be a sensitive indicator of compensated intravascular coagulation or systemic fibrinolysis induced by infusion of streptokinase. Clinical implications of these findings are discussed.
mesh_terms: D001779:Blood Coagulation Factors / Q000032:analysis*; D003429:Cross Reactions; D004211:Disseminated Intravascular Coagulation / Q000276:immunology; D005170:Factor X / Q000032:analysis*; D005260:Female; D006023:Glycoproteins / Q000032:analysis*; D006402:Hematologic Diseases / Q000276:immunology*; D006487:Hemostasis; D006801:Humans; D007700:Kinetics; D008107:Liver Diseases / Q000276:immunology; D008180:Lupus Erythematosus, Systemic / Q000276:immunology; D011247:Pregnancy; D011486:Protein C; D011863:Radioimmunoassay; D013300:Streptokinase / Q000494:pharmacology; D014859:Warfarin / Q000494:pharmacology
chemical_list: D001779:Blood Coagulation Factors; D006023:Glycoproteins; D011486:Protein C; D014859:Warfarin; D005170:Factor X; D013300:Streptokinase