BRAIN-ALUMINIUM CONCENTRATION IN DIALYSIS ENCEPHALOPATHY

Brain-aluminium concentrations were found to be significantly higher in 7 patients dying with dialysis encephalopathy (mean 15·9 μg aluminium/g dry weight) than in 11 dialysed controls (4·4 μg/g) and in 2 uræmic patients who were not dialysed (2·7 μg/g). The grey matter from the patients with dialysis encephalopathy contained about three times as much aluminium as white matter. The results suggest that dialysis with untreated and/or softened tap-water (aluminium concentration 0·1-1·2 mg/l) makes the major contribution to brain-aluminium levels; dialysis with deionised water (aluminium concentration normally less than 0·02 mg/l) and intake of phosphate-binding Al(OH)3 gel are less important. Brain aluminium levels remain elevated for up to four years after restoration of good renal function by transplantation. The association of dialysis encephalopathy with high levels of aluminium in the brain and in the dialysis water emphasises the potential neurotoxicity of aluminium in man.