source: University College London summary/abstract:
AA amyloidosis was previously known as secondary amyloidosis, or reactive systemic amyloidosis. It occurs in patients who have suffered from prolonged, chronic inflammatory or infectious diseases for many years. Most patients with AA amyloidosis have amyloid deposits in their kidneys which disrupt the kidney structure and cause problems with kidney function, most commonly protein in the urine. There are always amyloid deposits in the spleen, which may be enlarged. There may also be amyloid deposits in other parts of the body, which usually do not cause symptoms.
The fibrils found in the amyloid deposits are formed from a protein called amyloid A protein which is derived from a normal blood protein of unknown function, called serum amyloid A protein (SAA). SAA, which is produced in the liver, is found in very small quantities (less than 5 mg per litre) in the blood of all healthy people. But in response to many kinds of inflammation, infection or injury in the body, SAA production increases greatly, along with the production of another normal trace protein called C-reactive protein (CRP). Production of some other blood proteins also increases, although to a much smaller extent, as part of this normal reaction to disease, which is called the acute phase response. read more