UNUSUAL BLEEDING MANIFESTATIONS IN A CASE OF PRIMARY AMYLOIDOSIS WITHFACTOR-X DEFICIENCY BUT ELEVATIONS OF IN-VIVO MARKERS OF THROMBIN FORMATION AND ACTIVITY

We describe a case of primary amyloidosis (AL) with severe factor X (F X) deficiency in an amateur cyclist presenting with muscular pain at r est and ecchymoses in his legs. No circulating inhibitor of FX was fou nd by mixing studies and there was no deficiency of other vitamin K-de pendent coagulation factors and inhibitors or of alpha(2)-antiplasmin. Thrombin-time and reptilase time were abnormally prolonged and were n ot corrected by mixing with normal plasma. Administration of plasma or prothrombin complex concentrate (PCC) were unsuccessful in controllin g bleeding: the apparent half-life of transfused FX was 6 minutes. Res ting resulted in cessation of muscular pain and bleeding. Renal and ca rdiac deterioration led the patient to death 3 years after presentatio n. No further bleeding manifestations did occur during this period. FX levels remained consistently below 3%, but prothrombin fragment 1.2 a nd thrombin-antithrombin complex - measured at distance from PCC admin istration and prior to deterioration of renal and cardiac function - w ere markedly elevated. At autopsy, disseminated amyloidosis was found with sparing of the skeletal muscles and of the skin. This is the firs t report of increased in vivo prothrombin activation and activity in A L-associated FX deficiency.