Elsevier

Thrombosis Research

Volume 45, Issue 6, 15 March 1987, Pages 783-790
Thrombosis Research

Paper
Decline of proteins C and S and factors II, VII, IX and X during the initiation of warfarin therapy

https://doi.org/10.1016/0049-3848(87)90088-0Get rights and content

Abstract

Oral anticoagulants achieve an antithrombotic effect only several days after initiation of treatment. A rapid decline of the vitamin-K dependent natural anticoagulants (proteins C and S) during this period might result in a prothrombic phase. We addressed this question by measuring the rates of decline of these proteins, as well as the vitamin K dependent procoagulants, in two groups of patients: A “high dose group” (n=7), who received a single 40 mg dose of warfarin, and a “low dose group” (n=20), who received daily individually adjusted doses. In the high dose group an early and marked decline of factor VII:C and protein C antigen was observed, while levels of the other vitamin K dependent factors were still relatively high. In the low dose group, all these proteins declined more gradually. Mean ± SD of protein C antigen level at 46 hr was 56±12% in the low dose group, and only 44±6% (p<0.05) in the high dose group. We conclude that during the initiation of warfarin therapy there is a transient prothrombotic phase, which is less marked in patients given daily adjusted doses.

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