The Prothrombin Consumption Test: A Simplified Technic

Abstract

The prothrombin consumption test, or serum prothrombin time detn., is based on the fact that prothrombin is almost completely consumed during the clotting of normal blood. Such consumption is greatly reduced in hemophilia, thrombocytopenic purpura, and allied conditions. A deficiency of any of the factors (or their precursors) involved in the conversion of prothrombin to thrombin will cause a deficiency in prothrombin consumption. Previous methods of determining prothrombin consumption are tedious in respect to time and reagents. In the present technic venous blood is collected as in the ordinary Lee and White detn. of clotting time. After clotting at room temp., the blood stands for the remainder of an hour at 37[degree]C, and the separated serum is incubated an additional 10 min. at 37[degree]C. The serum is then added to tubes containing equal parts of thromboplastin, Ca, and prothrombin-free (treated with a stable suspension of BaSO4) plasma. The clotting time of the mixture is the serum prothrombin time, normally from 25 to 50 sec. This value is self-sufficient, but may be converted to serum prothrombin concn. and then to prothrombin consumption. The serum prothrombin time is much less than 25 sec. when prothrombin consumption is impaired.