Acquired factor X deficiency in patients with amyloid light-chain amyloidosis: incidence, bleeding manifestations, and response to high-dose chemotherapy

Acquired deficiency of factor X occurs in patients with systemic amyloid light-chain (AL) amyloidosis, presumably due to adsorption of factor X to amyloid fibrils, Of 368 consecutive patients with systemic AL amyloidosis evaluated at Boston Medical Center, 32 patients (8.7%) had factor X levels below 50% of normal, Eighteen of these patients (56%) had bleeding complications, which were more frequent and severe in the 12 patients below 25% of normal; 2 episodes were fatal, Ten factor X-deficient patients received high-dose melphalan chemotherapy followed by autologous stem cell transplantation. Of 7 patients alive 1 year after treatment, 4 had a complete hematologic response, and all 4 experienced improvement in their factor 4 levels, One of 2 additional patients with partial hematologic responses had improvement in factor X, Thus, aggressive treatment of the underlying plasma cell dyscrasia in AL amyloidosis can lead to the amelioration of amyloid-related factor X deficiency. (Blood, 2001;97: 1885-1887) (C) 2001 by The American Society of Hematology.