Factor IX and thrombosis.

Fractionation technology has made Factor IX concentrates available. In addition to a very high incidence of hepatitis, thrombosis is being recognized as a consequence of their use. Contradictory reports exist in the literature as to the incidence of thrombotic events. A recent study of thrombohemorrhagic phenomena after infusion with Factor IX concentrates in patients with congenital Factor IX deficiency (hemophilia B) or liver disease, revealed an incidence of twenty episodes in 188 cases (11%). It is imperative to delineate the thrombogenic factors and find methods for their removal to insure the safety of Factor IX products.