Dear Dr. Roach: Many members of my family and I have protein S deficiency and are prescribed warfarin. We are aware of the effects that food, exercise and medicines have in reaction to warfarin. Several of us have INR meters and do our testing at home. I have been on warfarin since 1991, with only a couple of clots, usually when dehydrated.
My grandson was on Eliquis, and had a DVT despite this, so he is back on warfarin. It is my understanding that none of the other “blood thinners” are testable to determine INR. Why do doctors prescribe them for protein S deficiency? Aren’t they approved just for atrial fibrillation? Why would a doctor prescribe Lovenox and warfarin together for over a year for my grandson? Hematologists, not internists, should be the doctors to treat protein S deficiency. — A.C.G.
Answer: Most people have probably not heard of protein S or protein C, but these are important regulators of the body’s capacity to form a clot. Unlike the other clotting factors, these act AGAINST the blood clotting cascade and so help prevent inappropriate clotting in the body. When people have low levels of either of these proteins, they are at risk for developing a blood clot, such as a deep venous thrombosis or pulmonary embolism.