Trace elements in end-stage renal disease - 1. Methodological aspects and the influence of water treatment and dialysis equipment

For human beings trace elements are essential nutrients with a gamut of fun ctions. They are for instance indispensable components of many enzymes, so they have some regulatory functions and they may affect immune reactions an d free radical generation. Altered blood levels of different trace elements have been described in patients with advanced renal failure and especially in those treated by different kinds of renal replacement therapy. Altered renal function may result in impaired renal excretion of trace elements and their accumulation or depletion in the body. The dialysate concentrate and water used for preparing the dialysate may be an important source of the a ccumulation or depletion of trace elements in dialyzed patients. The gain o r loss of trace elements during dialysis depends on the gradient between th e ultrafiltrable fraction of a particular element in serum and ifs concentr ation in the dialysis fluid, and also on the type and permeability of the d ialysis membrane. There are some methodological problems concerning the han dling and storing of blood samples and measurement techniques leading to th e rather inconsistent results of different studies concerning trace element s in renal disease. Geographical variations and environmental contamination of soil and water and different dietary habits may significantly influence trace elements in these patients. The abnormalities of trace elements are primarily the result of uremia, and they may be further modified and someti mes greatly exacerbated by the dialysis procedure.