What is beta-2-microglobulin (beta-2m) amyloidosis?

Updated: Nov 14, 2019
  • Author: Anita Basu, MD, FACP; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Answer

Beta-2 ̶ microglobulin (beta-2m) amyloidosis is a disabling condition that affects patients undergoing long-term hemodialysis (HD) or continuous ambulatory peritoneal dialysis (CAPD). [1, 2, 3] Case reports involving patients with near ̶ end-stage renal disease also exist. The condition does not affect individuals with normal or mildly reduced renal function or patients with a functioning kidney transplant. Beta-2m amyloidosis evolves predictably over time and is rare in the first few years of HD. (See Etiology.)

Beta-2m is a major constituent of amyloid fibrils. [4] Through accumulation, it invades synovial membranes and osteoarticular sites. As a result, it causes destructive osteoarthropathies, such as carpal tunnel syndrome, flexor tenosynovitis, subchondral bone cysts, and erosions, as well as pathologic fractures. (See Etiology, Prognosis, and Presentation.)

Visceral involvement has been found in sites such as the gastrointestinal (GI) tract, heart, and tongue, but overt manifestations are rare. (See Presentation and Workup. The most severe complication involves beta-2m amyloid deposits destroying paravertebral ligaments and intervertebral discs, which can result in paraplegia. Cardiac involvement, with subsequent fatal arrhythmias, and massive GI bleeding have been described.

Symptomatic relief in patients with beta-2m amyloidosis can be provided with analgesic and anti-inflammatory medication, physical and occupational therapy, and surgical procedures. Renal transplantation is the treatment of choice. See Treatment.


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