Protein C and protein S

The diagnosis of deficiency of either protein C or protein S should be considered in patients who have recurrent venous thromboembolic disorders but in whom no obvious risk factors for thrombosis could be found. The thrombotic process will respond in the usual manner to aggressive heparin therapy, and, once controlled, the patient can then be placed on warfarin therapy on a long-term basis. However, for reasons already mentioned, a loading dose should not be given and the initiation of warfarin should be covered by adequate heparin therapy. Protein C and protein S are present in 'prothrombin complex' preparations and may be used as replacement therapy on a short-term basis. Since their life-span is short, frequent infusion is needed. Recombinant protein C preparations may be available in the near future. For those patients with protein C or protein S deficiency who do not manifest thromboembolism, there is no sufficient evidence at this time to place them on prophylactic treatment with warfarin.