Protein C deficiency is a rare genetic trait that predisposes to thrombotic disease. It was first described in 1981. The disease belongs to a group of genetic. INTRODUCTION. Protein C deficiency is associated with a small percentage of cases of inherited thrombophilia, as well as the even more uncommon findings of warfarin. Anticoagulation proteins C and S. Esmon CT(1), Vigano-D'Angelo S. Protein S; Thrombosis/physiopathology; Warfarin/adverse effects; Substances. Anticoagulants; For this test, patients must be on a stable dose of Coumadin for at least two weeks. If patient has not received Coumadin for the past 2 weeks, see Protein C, No. Protein C is a substance that prevents blood clotting. A blood test can be done to see how much of this protein you have in your blood. Patient Education Blog. or on warfarin, low a low protein C level may a found. How Do You Test for Protein C Deficiency? Protein C is a normal substance in the body that prevents blood clotting. A blood test can be done to see how much of this protein you have in your blood. Warfarin, also known by the brand names Coumadin among others, is an anticoagulant normally used in the prevention of thrombosis and thromboembolism, the formation of. Tests for protein C and protein S are two separate tests that are often performed together to help investigate a possible excessive clotting. Testing is accomplished with a blood. initial treatment with warfarin alone in people with protein C or protein S deficiency may temporarily make.