Amyloidosis (type A) is by far the most important renal complication arising from rheumatological conditions such as rheumatoid arthritis. It may follow any inflammatory condition except lupus and ulcerative colitis, but is particularly common in rheumatoid arthritis, when it is a major contributor to morbidity and a common cause of death. It may also complicate ankylosing spondylitis, more rarely psoriatic arthropathy, and very rarely Behet's syndrome.
Amyloidosis may follow prolonged joint or bone sepsis/infection, particularly when this has lasted for several years. However, in rare cases a devastating renal amyloidosis with massive protein excretion in the urine and even renal failure may arise within weeks of established sepsis.
In general, once amyloid has been deposited within the kidney it does not regress, but there is some evidence for partial resolution in occasional cases.