Trace elements and hemodialysis.

M.H. Gault, Faculties of Medicine and Geology, Memorial University, St. John’s, Newfoundland (Canada) Dear Sir, Hoskawa et al. [1] discuss ‘Trace elements and complications in patients undergoing chronic hemodialysis’, in relation to increased serum values for aluminum and silicon, and low serum values for zinc, manganese and nickel. They mention that these patients were on fiber dialyzers 5 h, three times a week, that diet and illness can influence values for Zn, Mn, Ni and Si and that it is important to have low dialysate levels for Al and Si. We would like to point out some other factors which need to be considered in interpretation of the results of body fluid values of trace elements in dialysis patients. First, differences have been reported which depend on the sample analyzed [2]. For instance, differences have been found between serum and packed red cells for cobalt, rubidium, selenium, and zinc. Zinc was high in red cells but low in serum [2]. Secondly, results may be influenced also by residual renal function, the dialyzer membrane and size, the nature of the water used for the preparation of the dialysate, the method(s) of purification, and the composition of the concentrate. Sabbioni et al. [3] found that the salts used for preparation of the dialysate were the main source of metal contamination. Table 1. Comparison of trace elements in water prepared by deionization and reverse osmosis (R/O), with that collected after mixing with concentrate Element Mass