TOPIC DISCUSSION: Amyloidosis and Factor X deficiency

Whats the relation of the above two? AL Amyloidosis can present with Nephrotic syndrome and cardiac dysfunction that we are very aware of. Hepatic and splenic involvement cause organomegaly but little functional impairment.  Hemorrhagic manifestations are primarily due to sub-endothelial deposition of amyloid leading to capillary fragility and hemorrhage.  The bleeding time is typically prolonged but platelet aggregation and von Willebrand functional activity are normal. A rare complication is an acquired factor X deficiency state resulting from factor X adsorption to the amyloid fibrils in the vasculature. Residual factor X levels range from 2% to 50%. As a result, both the PT and aPTT are prolonged but the thrombin time and fibrinogen concentration are normal. Mixing studies of the patient's plasma and normal plasma correct the abnormal PT and aPTT, suggesting a factor deficiency state; but infusion of factor X results in a rapid loss of factor X activity. Factor IX deficiency has been reported as well.
So if someone has Factor X def and unexplained: Amyloidosis can be in the differential diagnosis. The thought was that factor X deficiency associated with systemic amyloidosis is due to binding of factor X to body tissue, probably within the circulatory system.

The NEJM article from 1977 first was to note this association in Amyloidosis. 
http://www.nejm.org/doi/full/10.1056/NEJM197707142970203
http://bloodjournal.hematologylibrary.org/cgi/content/full/97/6/1885