Conditions determining end products of prothrombin activation in serum

¹ Department of Laboratories, Milwaukee County Hospital; Departments of Medicine and Physiology, Marquette University School of Medicine, Milwaukee, Wisconsin; and Department of Medicine, Henry Ford Hospital, Detroit, Michigan

When blood clots normally such a small amount of prothrombin and small quantity of accelerators remain in the hour-old serum that the prothrombin consumption test is prolonged. When blood from a severe coagulation abnormality clots, prothrombin and fibrinogen are both found in serum. When the blood from milder coagulation abnormalities or from transfused severe coagulation abnormalities clots no prothrombin remains in the serum but quantities of the prothrombin-like derivative appear. It is suggested that this component may be a derivative of prothrombin, and a comparison with prothrombin has been undertaken. Studies carried out using disulfide-linkage inhibitors, known to inhibit prothrombin activation, also inhibit the coagulation system supported by this new component. The prothrombin-like derivative is not stable at –25 C for more than a few days whereas prothrombin stored under similar conditions is stable indefinitely.