In familial amyloidosis, these are strands of prealbumin. In secondary amyloidosis, a serum protein called serum amyloid A is produced. These excess strands then form relatively insoluble beta-pleated sheets which are deposited in various tissues. It is felt that phagocytic cells may help to process these proteins through lysosomal digestion into fragments capable of forming amyloid. These deposits then cause disease in various organs by interfering with their function.
Amyloidosis can affect virtually any organ or tissue in the body.
The most common presenting symptoms are fatigue or weakness, weight loss, ankle edema, dyspnea, paresthesias, and light-headedness or syncope. The most common physical findings are hepatosplenomegaly, edema, macroglossia, orthostatic hypotension and purpura. A number of associated syndromes are frequently seen, including carpal tunnel syndrome, peripheral neuropathy, nephrotic syndrome, congestive heart failure and sprue. The most significantly involved organ systems are the kidneys and heart. Failure of these two systems also constitutes the two leading causes of death.