Dialysis-Related Amyloidosis(kidney cancer stones)

Normal kidneys filter and remove excess small proteins from the blood, thus keeping blood levels normal. When the kidneys don't work properly, as in patients receiving dialysis, one type of small protein calle beta-2-microglobulin builds up in the blood. When this occurs, beta-2-microglobulin molecules may join together, like the links of a chain, forming a few very large molecules from many smaller ones. These large molecules can form deposits and eventually damage the surrounding tissues and cause great discomfort. This condition is called dialysis-related amyloidosis (DRA).

DRA is relatively common in patients, especially older adults, who have been on hemodialysis for more than 5 years. Hemodialysis membranes that have been used for many years don't effectively remove the large, complex beta-2-microglobulin proteins from the bloodstream. Newer hemodialysis membranes, as well as peritoneal dialysis, remove beta-2-microglobulin more effectively, but not enough to keep blood levels normal. As a result, blood levels remain elevated, and deposits form in bone, joints, and tendons (the tissue that connects the muscle to the bone). DRA may result in pain, stiffness, and fluid in the joints. Patients with DRA may also develop hollow cavities, or cysts, in some of their bones; these may lead to unexpected bone fractures. Amyloid deposits may cause tears in ligaments and tendons. Most patients with these problems can be helped by surgical intervention.

Half of the people with DRA also develop a condition called carpal tunnel syndrome, which results from the unusual buildup of protein in the wrists. Patients with this condition may experience numbness or tingling, sometimes associated with muscle weakness, in their fingers and hands. This is a treatable condition.