Abstract

Serial nerve conduction velocities in the peroneal and ulnar nerves have been measured in 10 patients on regular dialysis treatment over a three year period. Each patient alternated between phases on dialysis with magnesium-containing dialysate (1·5-1·7 m-equiv/l.) and phases on `magnesium-free' dialysate (0·2 m-equiv/l.). Plasma magnesium concentrations were high both pre- and post-dialysis during magnesium-containing dialysis, and normal to low on magnesium-free dialysis. All patients had defects in nerve conduction, mainly asymptomatic. Increases in nerve conduction velocity coincided with magnesium-free dialysis, and decreases occurred when the patients reverted to magnesium-containing dialysate. The significance of the correlation by the sign test was P<0·0005. It is concluded that extracellular magnesium levels can influence the rate of nerve conduction in vivo.