Plasma or whole blood concentrations of trace elements in patients treated by haemodiafiltration with on-line prepared substitution fluid.

Large membrane pores and large quantities of reinfusion fluids can influence the dialytic balance of trace elements in haemodiafiltration (HDF). As there are no studies in HDF with on-line produced reinfusate, we studied plasma or whole blood (*) concentrations of trace elements (Al, Cd*, Cr* and Se: microg/l; Cu, Pb* and Zn*: microg/dl) of 24 on-line HDF, 20 haemodialysis (HD) patients and 66 490 normal subjects (N). The concentrations of Al (11.7+/-9.5), Cd (0.73+/-0.59) and Cr (6.5+/-6.9) were significantly greater in on-line HDF patients than in normal subjects (6+/-0.4; 0.6+/-0.2; 0.5+/-0.02), but similar to those of HD patients. In on-line HDF patients, Cu (85.3+/-17.7), Pb (8+/-4.6), Se (68+/-27) and Zn (546+/-103) concentrations were less than in normal subjects (108+/-3.4; 11+/-0.8; 95+/-1.8; 673+/-23), and those of Cu and Zn were also less than in HD patients (99.5+/-16.8; 670+/-65). At the end of an on-line HDF treatment (42-69 studies), there was a significant increase in Al (from 12.8+/-9.1 to 15.4+/-8.3), Cr (from 7.2+/-6.4 to 9.5+/-7), Cu (from 97.3+/-21.5 to 109.4+/-27.2) and Zn (from 577+/-108 to 619+/-117). A longitudinal study (n = 16-18) for 12-30 months documented stable concentrations of Al, Cd, Cr, Se and Zn and a significant increase of Cu and Pb to normal concentrations. In conclusion, our on-line HDF patients have elevated Al, Cd, Cr and decreased Cu, Pb, Se, Zn concentrations in plasma or whole blood determinations. Cu and Pb normalize with time; the other trace elements remain stable as documented by numerous determinations. As the values for on-line HDF patients are similar to those of HD patients, the level of accumulation or depletion of trace elements in on-line HDF can be considered as safe as in HD; the increase in Al, Cd, Cu and Zn at the end of treatment may be an expression of the increase of those trace elements linked to proteins.