Simultaneous conversion of dialysate magnesium concentration from 1.0 to 1.2 mEq/L and dialysate calcium concentration from 3.0 to 2.6 mEq/L and changes in serum mineral and bone metabolism markers in patients undergoing maintenance hemodialysis: a retrospective study

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Abstract Background The impact of simultaneous conversion of dialysate calcium (DCa) concentration from 3.0 to 2.6 mEq/L and dialysate magnesium (DMg) concentration from 1.0 to 1.2 mEq/L on mineral and bone metabolism in patients undergoing hemodialysis remains unknown. Methods We retrospectively recruited 52 patients undergoing hemodialysis who experienced a conversion of dialysates from dialysate A (DCa 3.0 mEq/L and DMg 1.0 mEq/L) to dialysate B (DCa 2.6 mEq/L and DMg 1.2 mEq/L) at a hemodialysis center. The effects of changing the DCa and DMg concentrations on serum bone and mineral parameters were examined over 7 months. Results A total of 48 patients were finally analyzed. After changing the dialysate, serum magnesium (Mg) levels increased significantly from 2.31 ± 0.38 at 0 months to 2.54 ± 0.43 mg/L at 7 months, and serum calcium (Ca) levels decreased significantly from 9.51 ± 0.80 at 0 months to 9.14 ± 0.57 mg/dL at 7 months, with no change in serum intact parathyroid hormone levels. Notably, the serum Ca-to-serum-Mg ratio and serum Ca × inorganic phosphate-to-serum-Mg ratio decreased significantly after dialysate conversion. Around 10% of patients started or increased the dose of vitamin D receptor activators, and 18% of patients started or increased the dose of Ca-based phosphate binders. Notably, the serum Mg levels in three patients exceeded 3.5 mg/dL during the observation period. Conclusions Conversion of DCa from 3.0 to 2.6 mEq/L and DMg from 1.0 to 1.2 mEq/L lowers serum Ca levels and increases serum Mg levels, possibly leading to decreased Ca loading and increased Mg storage among patients undergoing hemodialysis.