Observations on the characteristics of an unusual circulating anticoagulant.

Abstract

Abstract In a patient with subacute bacterial endocarditis and cryoglobulinemia, the whole blood clotting time was prolonged at 25 ° C. but was usually normal at 37 ° C. The prolonged clotting time was attributed to the presence of a circulating anticoagulant which was active in whole blood at 25 ° C. but not at 37 ° C. However, the anticoagulant was demonstrable at both temperatures in the absence of the formed elements of the blood. The anticoagulant appeared to inhibit the conversion of prothrombin, an effect opposed by thromboplastin and by the formed elements of the blood.