RT Journal Article SR Electronic T1 Acquired factor X deficiency in systemic amyloidosis JF Cleveland Clinic Journal of Medicine JO Cleve Clin J Med FD Cleveland Clinic SP 399 OP 406 VO 54 IS 5 A1 Lucas, Fred V. A1 Fishleder, Andrew J. A1 Becker, Richard C. A1 Cavalier, Deborah S. A1 Tubbs, Raymond R. YR 1987 UL http://www.ccjm.org/content/54/5/399.abstract AB Acquired factor X deficiency has been described in association with primary amyloidosis in a small number of patients. Although readily corrected in vitro by mixing patient plasma with normal plasma, the deficiency is not easily corrected in vivo because transfused factor X is rapidly cleared from the circulation. It has been suggested that the mechanism underlying this phenomenon may be the selective binding of factor X to amyloid and its consequent removal from the circulation. Two cases of primary amyloidosis and coexistent acquired factor X deficiency are reported. Immunostains for factor X and immunoglobulin light chains showed the coagulation factor in the region of the amyloid deposits. The findings directly support the hypothesis that factor X deficiency in primary amyloidosis is caused by clearance of factor X by binding to amyloid fibrils.