Behavior of beta 2-microglobulin in patients with chronic renal failure undergoing hemodialysis, hemodiafiltration and continuous ambulatory peritoneal dialysis (CAPD).

beta 2-microglobulin (beta 2-m) is the major component of a new form of amyloid deposit found in carpal tunnel syndrome and dialysis arthropathy of long-term hemodialysis patients. In 52 patients on maintenance hemodialysis, serum beta 2-m concentration was elevated to 37.9 +/- 1.4 (normal 1.2 +/- 0.6) mg/l. It was correlated with the time on hemodialysis (r = 0.43, p less than 0.01) and was inversely correlated with residual renal function (r = 0.87, p less than 0.001). In 20 patients on CAPD, beta 2-m likewise was increased to 31.6 +/- 2.3 mg/l; daily elimination by dialysate was only 34 mg (normal 150 mg). Hemodialysis with a cuprophane membrane caused a rise in serum beta 2-m, whereas hemodiafiltration with a polysulfone membrane performed in 5 patients over 2 1/2 months was accompanied by a decrease in serum beta 2-m from 39.5 +/- 0.7 to 29.7 +/- 1.0 mg/l predialysis (19.1 +/- 1.1 postdialysis). On the other hand, beta 2-m elimination reached only approximately 100 mg per day in spite of markedly elevated serum levels. It is concluded that serum beta 2-m is massively elevated in long-term hemodialysis and CAPD patients; contrary to routine hemodialysis with cuprophane membranes, newer more permeable membranes will permit some elimination of beta 2-m. However, based on quantitative considerations it seems difficult to obtain beta 2-m concentrations in the high normal or moderately elevated range with present day techniques.