Ten years of prophylactic treatment with fresh-frozen plasma in a child with chronic relapsing thrombotic thrombocytopenic purpura as a result of a congenital deficiency of von Willebrand factor-cleaving protease

We report the results of 10 years of prophylactic fresh-frozen plasma (FFP) infusion therapy in a 14-year-old girl with chronic relapsing thrombotic t hrombocytopenic purpura (TTP). in whom a severe congenital von Willebrand f actor (VWF)-cleaving protease deficiency has been documented, Severe haemol ytic crises triggered by infections were prevented and her present renal an d neurological functions have been preserved, Sequential measurements prote ase activity and platelet count after FFP infusion led us to conclude tenta tively that 5% may be sufficient to degrade very large and adhesive VWF mul timers.