Effect of vitamin D treatment on magnesium levels in chronic hemodialysis patient; a double blind controlled clinical trial

Introduction: The homeostasis of magnesium (Mg) is impaired in chronic kidney disease (CKD) and it has been suggested that intestinal absorption of Mg may be affected by vitamin D status. 25-Hydroxy vitamin D or 25(OH)D deficiency is common in patients undergoing chronic hemodialysis; however the efficacy of nutritional vitamin D supplementation on Mg level in this population remains uncertain. Objectives: The aim of this study was to evaluate the effect of vitamin D treatment on Mg levels in chronic hemodialysis patients. Patients and Methods: This randomized clinical trial study was conducted on 69 chronic hemodialysis patients (mean age of 56.93 ±12.26 years) with serum 25-hydroxy vitamin D levels <30 ng/mL. The patients were randomly assigned to one of treatment groups of oral vitamin D3- 50 000 units per week (n=35; experimental group) or 500 mg calcium D3 tablets, every 12 hours (n=34; control group) for three months. At the beginning and end of the treatment period, the levels of serum 25-hydroxy vitamin D and the levels of Mg, calcium, phosphorus and intact parathyroid hormone (iPTH) were measured in two groups. Results: In both groups, serum vitamin D levels increased significantly after treatment (P<0.0001 for both groups), however after three months of treatment, in the experimental group the levels of vitamin D were significantly higher than the patients in the control group (57 ng/mL versus 28 ng/mL; P<0.0001) and the median increase of vitamin D after treatment in the experimental group was significantly higher than the control group (40 ng/mL versus 10.5; P<0.0001). Serum Mg levels before and after treatment were not significantly different between two groups (P=0.880 and P=0.434). In this study, we found no significant correlation between serum vitamin D level with serum Mg, calcium, phosphate, and parathyroid Hormone levels (P>0.05). Conclusion: Our study shows that oral vitamin D therapy can increase 25(OH)D levels in maintenance hemodialysis patients without significant alterations in serum calcium, phosphate, magnesium and parathyroid hormone during a 12-week period. Trial Registration: Registration of trial protocol has been approved by the Iranian registry of clinical trial (#IRCT20210314050698N1; https://en.irct.ir/trial/55159, local ethical code# IR.SKUMS.REC.1397.181).