Factor II, VII, IX and X concentrations in patients receiving long term warfarin.
Using standard one stage clotting assays the concentrations of factors II, VII, IX and X were determined in 37 patients stabilised on warfarin for between three months and 17 years. Contrary to popular belief, the concentrations were not equally depressed, with factor X the lowest, factor II at intermediate value, factors VII and IX the highest. Some 71% of the variance of the British corrected ratio (BCR) could be accounted for by measurement of the factors assayed. Analysis of this variance showed 91% of the explained variance attributable to factor II, 7% to factor VII, 1.6% to factor IX and 0.4% to factor X. With the sudden and recent withdrawal of human thromboplastin, investigation of the sensitivities of the animal thromboplastins to changes in vitamin K dependent factors in orally anticoagulated patients is needed to ensure that the potentially alarming falls in factors II and X in these patients are being adequately detected.
D000328:Adult; D000368:Aged; D001779:Blood Coagulation Factors / Q000032:analysis*; D005164:Factor IX / Q000032:analysis; D005167:Factor VII / Q000032:analysis; D005170:Factor X / Q000032:analysis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011516:Prothrombin / Q000032:analysis; D013997:Time Factors; D014859:Warfarin / Q000008:administration & dosage* / Q000627:therapeutic use
D001779:Blood Coagulation Factors; D014859:Warfarin; D005167:Factor VII; D011516:Prothrombin; D005164:Factor IX; D005170:Factor X