Until recently, almost all patients with end-stage kidney failure who were treated with dialysis for over five years developed so-called dialysis related amyloidosis. The amyloid deposits contain a protein called β2 (pronounced “beta 2”) microglobulin. This is a protein which is normally present on the surface of white blood cells and most other cells in the body. It is cleared from the blood only by the kidneys, but was not efficiently cleared from the blood by either artificial kidney machines (haemodialysis) or by peritoneal dialysis. Therefore, levels of this protein would build up in the blood over the years of dialysis, until it formed amyloid deposits. Current dialysis membranes and modern dialysis procedures have improved the clearance of β2 microglobulin. This type of amyloidosis is therefore becoming less common.
β2 microglobulin amyloid deposits in dialysis patients are always in and around the bones and joints, causing:
- carpal tunnel syndrome
- pain and stiffness in the large joints
- soft tissue masses
- bone cysts
- pathological fractures (broken bones after minimal trauma or even without trauma)
Very rarely this type of amyloid can involve the internal organs. β2 microglobulin amyloidosis has also been reported, rarely, in patients with chronic renal failure who have never been on dialysis.