Answer: Amyloid is an abnormal build-up or accumulation in various tissues of the body from several different proteins found in the blood. Amyloidosis is the name of the disease this accumulation causes. It is a problem with long-term patients on peritoneal and hemodialysis. The accumulation is abnormal because it leads to signs of damage to tissues and painful symptoms. The areas most involved in dialysis patients are the hands and wrists, shoulders, neck and lower back. Blood proteins of several types can cause amyloid deposits. Some proteins cause renal disease by involving the normal kidney and some are the result of persistent inflammation. In this article, I will write about the accumulation of a protein called beta-2 microglobulin (B2MG) in the tissues of dialysis patients. 

Patients on dialysis for 15 to 20 years start to notice a stiffness and often pain in their fingers and shoulders. They may have more trouble making a fist, buttoning shirts or tying shoes. It gets a little harder to reach behind the back or neck or raise the arms over the head. Pain in the shoulders upon lying down may interfere with sleep or dialysis treatments. Patients may also notice pain and/or numbness in the hands, which wakes them at night. This may be due to carpal tunnel syndrome from amyloid protein deposited in the wrist. Shaking the hands makes it temporarily better. Thus, develops the "stiff-person" syndrome of the long-term dialysis patient.  This stiffness and pain is due to deposits of amyloid.  More serious problems may follow when the spine in the neck and lower back become infiltrated with amyloid protein. Compression of the spinal cord leads to weakness in the legs when the lower spine is involved or arms and legs when the neck is the deposit site. This weakness can progress to paralysis, which is the inability to move at all.

The cause of the problem in dialysis patients is the buildup in the blood of a protein called beta-2 microglobulin (B2MG), which is eliminated by normal kidneys. This protein is produced when white blood cells are stimulated. One of the most common stimulations in hemodialysis patients is exposure of the blood to dialysis membranes. The experience with and causes of amyloid are less clear in patients on long-term peritoneal dialysis. The reasons amyloid settles where it does and why are under investigation, but the answers may provide methods for prevention and relief. 

Studies have shown that membranes with large holes (high flux) remove more of the B2MG molecules which cause the amyloid. That cannot be the only solution, however, because in 30 years of dialysis exposure I have never dialyzed on these membranes and am only moderately afflicted with amyloid. Most other patients that I have known to have been on dialysis for up to 30 years have been severely impaired by amyloid.

Dialysis is an oxidizing and thus an accelerated aging process. The use of antioxidants to prevent or slow down this aging has not been well studied in dialysis patients, but may be worth considering. Please check with your own physician to see if they may be beneficial to you.

Answer provided by A. Peter Lundin, MD. Dr. Lundin is a nephrologist at the State University of New York, Health Science Center in Brooklyn. He is a past president of AAKP and a member of the AAKP Medical Advisory Board. 

The Dear Doctor column provides readers with an opportunity to submit renal related health questions to healthcare professionals who specialize in the area of concern. The answers are not to be construed as a diagnosis and therefore, altercations in current healthcare should not occur until the patient's physician is consulted.

This article originally appeared in aakpRENALIFE, Volume 16 Number 5, March 2001.

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