Plasma Clearance Rates of Coagulation Factors VIII and IX in Factor-deficient Individuals

The plasma clearance rates of factors IX and VIII were determined in patients with hemophilia A and B who had received factor replacement by prolonged, continuous infusion of factor concentrates. The clearance rates were calculated by dividing the factor infusion rates by the steady-state plasma factor activities corrected for base-line factor activities. The mean factor IX clearance rate in eight factor IX-deficient patients was 233 mL/h (range 159 to 340 mL/h). The mean normalized clearance rate was 3.4 mL/h/kg. The mean factor VIII clearance rate in eight factor VIII-deficient patients was 294 mL/h (range 229 to 361 mL/h) and the mean normalized rate was 5.0 mL/h/kg. Both factors show linear relationships between the factor infusion rates and the steady-state plasma factor activities achieved.