COMBINED FACTOR-IX AND PROTEIN-C DEFICIENCY IN A CHILD - THROMBOGENICEFFECTS OF 2 FACTOR-IX CONCENTRATES

We have recently described an unusual situation which involved a combi nation of a factor IX and a protein C deficiency in a young child who presented, according to the bleeding tendency, as a hemophilia B patie nt. In this particular hemophiliac, baseline prothrombin fragment F-12 levels were unexpectedly elevated and increased after an injection o f a very high purity factor IX concentrate. This observation raised a question regarding the substitution schedule in the case of repeated i njections of factor IX, since the thrombotic tendency has been a major concern with some factor IX concentrates. We monitored factor IX, pro thrombin fragment F-1+2, and D-dimer plasma levels before and during t he 6 hr following the injection of an immunopurified factor IX concent rate. The results showed an increase in the F-1+2 levels after the fac tor IX injection, but an increase lower than previously observed with an ion-exchange chromatography-purified concentrate. Furthermore, the F-1+2 level returned to baseline value 6 hr after administration. This factor IX concentrate seems to be best for use in the patient where r epeated injections are involved (as employed during surgery). Moreover , the data point out the advantage of a monoclonal antibody-purified f actor IX concentrate over less purified concentrates in a specific sit uation,with regard to the thrombogenic risk. (C) 1995 Wiley-Liss, Inc.