Magnesium carbonate for phosphate control in patients on hemodialysis. A randomized controlled trial

Abstract

Background Magnesium salts bind dietary phosphorus, but their use in renal patients is limited due to their potential for causing side effects. The aim of this study was to evaluate the efficacy and safety of magnesium carbonate (MgCO 3 ) as a phosphatebinder in hemodialysis patients. Methods Forty-six stable hemodialysis patients were randomly allocated to receive either MgCO 3 (n = 25) or calcium carbonate (CaCO 3 ), (n = 21) for 6 months. The concentration of Mg in the dialysate bath was 0.30 mmol/l in the MgCO 3 group and 0.48 mmol/l in the CaCO 3 group. Results Only two of 25 patients (8%) discontinued ingestion of MgCO 3 due to complications: one (4%) because of persistent diarrhea, and the other (4%) because of recurrent hypermagnesemia. In the MgCO 3 and CaCO 3 groups, respectively, time-averaged (months 1-6) serum concentrations were: phosphate (P), 5.47 vs. 5.29 mg/dl, P = ns; Ca, 9.13 vs. 9.60 mg/dl, P \ 0.001; Ca 9 P product, 50.35 vs. 50.70 (mg/dl) 2 , P = ns; Mg, 2.57 vs. 2.41 mg/dl, P = ns; intact parathyroid hormone (iPTH), 285 vs. 235 pg/ml, P \ 0.01. At month 6, iPTH levels did not differ between groups: 251 vs. 212 pg/ml, P = ns. At month 6 the percentages of patients with serum levels of phosphate, Ca 9 P product and iPTH that fell within the Kidney Disease Outcomes Quality Initiative (K/DOQI) guidelines were similar in both groups, whereas more patients in the MgCO 3 group (17/23; 73.91%) than in the CaCO 3 group (5/20, 25%) had serum Ca levels that fell within these guidelines, with the difference being significant at P \ 0.01. Conclusion Our study shows that MgCO 3 administered for a period of 6 months is an effective and inexpensive agent to control serum phosphate levels in hemodialysis patients. The administration of MgCO 3 in combination with a low dialysate Mg concentration avoids the risk of severe hypermagnesemia.

Evaluation of Peripheral Vascular Calcification and Serum Magnesium Level in a Group of Egyptian Hemodialysis Patients

“…An experimental study demonstrated that dietary supplementation with Mg reduced medial calcification of the grafted aorta in the rat [22]. Potential benefits have also been attributed to Mg carbonate use as an effective, less toxic and less expensive phosphate binder in HD patients [23].…”

Hypomagnesemia in Hemodialysis Patients: Role of Proton Pump Inhibitors

“…Several past studies have suggested that hypermagnesemia, by increasing total body and bone magnesium, may lead to worsening of renal osteodystrophy [4], delayed nerve conduction [5], and pruritus [6], and that lowering plasma [Mg] can improve these abnormalities [4,5,6]. More recently, use of magnesium as an inexpensive phosphate binder [7,8,9,10,11] and the possible role of high magnesium in adynamic bone disease [12] have led to use of a lower dialysate [Mg]. Whereas mild hypermagnesemia is expected with use of a dialysate [Mg] of 1.5 mEq/l [13,14,15,16], a dialysate [Mg] of 1.0 mEq/l has generally been associated with either normal plasma [Mg] or mild hypermagnesemia [17,18].…”

Phosphate binders, past – present – future. A critical appraisal.

“…Magnesium is known for its protective action against calcification and it is not a surprise that has a favorable effect on vascular calcification. Either alone, [16] or in combination with calcium, is an effective phosphate binder. Nevertheless, caution is needed to avoid prescribing increased doses in order to avoid calcium burden.…”