Amyloidosis in patients of continuous ambulatory peritoneal dialysis

Dialysis amyloidosis is a common complication of long-term hemodialysis. Amyloid deposits have been associated with carpal tunnel syndrome, bone cysts, pathological fractures, destructive spondyloarthropathy, and peripheral arthropathy, and it has been demonstrated that the amyloid protein is beta(2)-microglobulin. Carpal tunnel syndrome (CTS) has been reported to occur with a similar frequency in both hemodialysis and continuous ambulatory peritoneal dialysis (CAPD) patients. Radiological bone lesions, similar to those described in HD patients with amyloid arthropathy, have also been reported in patiens on CAPD. However, amyloid deposits in the carpal tunnel, synovial membrane or bone have been histologically proven in only a few CAPD patients. The main aim of our study was to assess the prevalence of CTS and amyloid osteoarthropathy in patiens on CAPD. We studied 20 patients, aged 38-82 years (mean 58.8 years), who had been on peritoneal dialysis for between 2 and 88 months (mean 35.2 months), to investigate the prevalence of CTS and amyloid osteoarthropathy. The diagnostic criteria for amyloid arthropathy were: 1) histological confirmation of amyloid substance in synovial fluid and/or 2) bone cysts on radiographs with a diameter greater than or equal to 5 mm in the wrist, and greater than or equal to 10 mm in the shoulder knee and hip, in at least two joints, which cannot be explained by any other pathological condition. Five patients (25%) were found to have amyloid arthropathy, 2 of them had also CTS. Articular and systemic amyloid deposits reacting with anti-beta(2)-microglobulin were demonstrated in 1 patient at necropsy. Patients with amyloid osteoarthropathy were significantly older (69.8 vs 55.1 years old) (p < 0.05) than those without osteoarthropathy, also the age at the onset of dialysis treatment was statistically higher 9 (65.4 vs 52.2 years old) (p < 0.05). The duration of dialysis treatment (48.2 vs 30.9 months) and beta(2)-microglobulin levels (32.1 vs 25.7 mg/l) were not statistically significant. The results suggest than amyloid arthropathy occurs in patients on peritoneal dialysis even when dialysed for less than 5 years. Age at the onset of dialysis treatment and at time of assessment appears to be a majors predisposing factors in the development of amyloid osteoarthropathy.