Effects of low-dose magnesium oxide on elevated serum magnesium levels and improved constipation in hemodialysis patients: a single-center retrospective study

Abstract Background The prevention of hypomagnesemia is critical for improving the life expectancy of patients undergoing hemodialysis (HD). The administration of magnesium oxide (MgO) increases serum Mg concentrations; however, dose adjustments must be done carefully owing to the risk of hypermagnesemia in patients undergoing HD. Additionally, the laxative effects of low-dose MgO on constipation in these patients has not been reported. Therefore, in the present study, we investigated the effects of treatment with low-dose MgO on serum Mg concentration changes and the improvement of defecation in patients undergoing HD. Methods The present study was a single-center retrospective observational study of 43 patients undergoing maintenance HD at Shirasagi Hospital. The patients’ clinical characteristics, including serum Mg concentration, were obtained from the hospital’s electronic medical records. In the group who received MgO for constipation, the effectiveness of MgO as a laxative was categorized as effective, ineffective, or unknown on the basis of electronic medical records related to defecation. Results Of the 43 patients included in the present study, 23 were prescribed supplemental Mg to prevent hypomagnesemia or maintain mild hypermagnesemia and 19 to prevent constipation. All patients received diasylate with an Mg concentration of 1.0 mEq/L. Additionally, 37 patients (86%) were treated with 330 mg/day MgO. The serum Mg concentrations before and 1, 2, and 3 months after the start of MgO were 2.3 ± 0.2, 2.8 ± 0.4, 2.8 ± 0.5, and 2.8 ± 0.4 mg/dL, respectively (P