Use of magnesium hydroxide and low magnesium dialysate does not permit reduction of aluminum hydroxide during continuous ambulatory peritoneal dialysis.

In an effort to reduce the ingestion of aluminum in phosphate-binding antacids, we treated seven patients on continuous ambulatory peritoneal dialysis (CAPD) with low magnesium dialysate and phosphate binders containing both aluminum and magnesium hydroxide. The total amount of phosphate binders prescribed was adjusted to maintain the serum phosphorus at normal levels. The dose of magnesium hydroxide was limited by intolerable gastrointestinal side effects in six of the seven patients. One patient also developed symptomatic hypermagnesemia. When magnesium hydroxide was prescribed in tolerable doses, the mean aluminum dose was not significantly decreased compared with the dose when taking aluminum hydroxide alone. We conclude that substitution of magnesium hydroxide for aluminum hydroxide as a phosphate binder fails to reduce the dose of aluminum in most patients on CAPD.