Protein C antigen deficiency and warfarin necrosis

Recent reports have suggested a correlation between congenital protein C deficiency and tissue necrosis complicating oral anticoagulants (warfarin necrosis). The authors studied blood samples of 13 patients, obtained two weeks to more than six months after warfarin necrosis. Protein C antigens levels were assayed by an enzyme-linked immunosorbent assay method (Diagnostica Stago, France). Factors II, VII, IX, and X were assayed by functional methods, and IX and X additionally by immunologic methods. The results show that 11 of 13 patients with a history of tissue necrosis had low protein C levels, ranging from 23 to 69%, with the normal range being 70-140%. These results confirm that low protein C antigen levels are implicated in the pathogenesis of warfarin necrosis.