High-flux dialysis lowers plasma leptin concentration in chronic dialysis patients

Leptin is a protein produced by fat cells and involved in body weight regul ation, Plasma leptin is significantly higher in some hemodialysis (HD) pati ents than in normal controls. We examined the influence of dialyzer membran e biocompatibility and flux on elevated plasma leptin concentrations in hem odialysis patients. Employing a crossover design, leptin and tumor necrosis factor alpha (TNF alpha) revels were serially determined in eight chronic dialysis patients. Patients were dialyzed sequentially on low-flux cellulos ic (TAF) dialyzers, low-flux (F8) polysulfone, high-flux (F80B) polysulfone , then low-flux polysulfone and cellulosic dialyzers again. Mean leptin con centrations were similar when low-flux polysulfone or cellulosic dialyzers were employed (141.9 +/- 24.2 mu g/L versus 137.8 +/- 18.4 mu g/L, respecti vely (P = NS), In contrast, leptin fell significantly on the high-flux poly sulfone dialyzer (99.4 +/- 16.2 mu g/L) compared with cellulosic (P < 0.005 ), and low-flux polysulfone dialyzers (P < 0.02). Leptin clearance by the h igh-flux polysulfone dialyzer was significantly higher than the low-flux di alyzers (50.4 +/- 21.5 v -9.6 +/- 10.3 mL/min; P = 0.043), but did not acco unt fully for the 30% decline in plasma leptin during the high-flux arm of the study. Concentrations of TNF alpha. were lower when high-flux polysulfo ne dialyzers were employed, but there was no correlation of individual TNF alpha levels with leptin concentrations, High-flux dialysis lowers plasma l eptin concentrations an average of 30%, but biocompatibility does not influ ence leptin levels. The decrease in plasma leptin on high-flux dialysis can not be explained solely by enhanced clearance. (C) 1998 by the National Kid ney Foundation, Inc.