INCREASED SILICON LEVELS IN DIALYSIS PATIENTS DUE TO HIGH-SILICON CONTENT IN THE DRINKING-WATER, INADEQUATE WATER-TREATMENT PROCEDURES, ANDCONCENTRATE CONTAMINATION - A MULTICENTER STUDY

Background. Although silicon is considered as an essential element, li ttle is known about the basic effects and clinical significance of inc reased concentrations of the element in dialysis patients. Methods and results. In a multicentre study we found silicon levels in haemodialy sis (HD) patients to be markedly increased. In these patients silicon concentrations were significantly higher than those noted in subjects with normal renal function as well as in patients with chronic renal f ailure not yet in dialysis and patients treated by continuous ambulato ry peritoneal dialysis (CAPD). Moreover we noted that in both HD and C APD patients mean silicon levels differed from one centre to another. Also, was there in the HD population a significant difference in serum silicon levels among patients from different countries. In HD patient s differences in serum silicon levels were either due to the use of si licon contaminated dialysis fluids or an increased oral intake of the element mainly originating from the high silicon content of the drinki ng water. Silicon contamination of the dialysis fluid was found to be due to either the use of reverse osmosis membranes that insufficiently retain the element during water treatment or by the addition of conce ntrates containing high amounts of silicon. Using a recently developed high-performance liquid chromatographic/atomic absorption spectrophot ometric (HPLC/ETAAS) hybrid technique, we found silicon in serum to be present as a low-molecular-weight non-protein-bound component, which in the presence of a low silicon dialysate is adequately removed durin g treatment. Conclusions. The clinical relevance of increased serum si licon levels is not yet known and as such deserves further investigati on. In view of the controversy that exists on the element's assumed pr otective as well as toxic role in the development of some (aluminium-r elated) neurodegenerative diseases and its vital role in bone formatio n, monitoring of the silicon levels in serum, tap water, and dialysis fluids might become important.