Effects of Magnesium Supplementation on Kidney Function and Phosphate Levels in Children with Chronic Kidney Disease and Hyperphosphatemia: A Double-blind Randomized Clinical Trial

Background: Pediatric patients with chronic kidney disease (CKD) who have hyperphosphatemia may experience further deterioration in kidney function. This study aims to investigate the effect of magnesium supplementation on the reduction of phosphate levels and improvement of kidney function in children with CKD and hyperphosphatemia, compared to a placebo. Methods: A randomized, double-blind, placebocontrolled trial was conducted at Pediatric Ward in our setting during March-July 2022. We compared oral magnesium supplementation (6 mg/kg body weight/day for two months) with a placebo in children with CKD and hyperphosphatemia (ages 1-18 years old). Patients who were on dialysis and had serum magnesium levels of <1.6 mg/dL and >2.4 mg/dL, and were allergic to magnesium supplementation were excluded. A paired T-test and the Wilcoxon signed-rank test were used for statistical analysis. Results: We collected 31 children in the experimental group and 29 children in the placebo group. Phosphate levels were decreased in both the magnesium supplementation and placebo groups (5.4 ± 0.9 to 4.8 ± 1.1 mg/dL; p-value = 0.001 and 5.1 ± 0.6 to 4.3 ± 1.2 mg/dL; p-value=0.003). However, when compared between groups, the reductions were not significantly different (0.7 vs 0.8; p-value=0.935). A significant improvement was found in kidney function in both groups using estimated Glomerular Filtration Rate (eGFR) (83.4±25.3 to 118.8±52; p-value=<0.001 and 86.3±28.1 to 96.9 ± 35.8; p-value=0.004), and the reductions were significantly different (35.4 vs 10.7; p-value=0.045). Conclusion: Magnesium supplements have considerably lower phosphate levels and markedly improved kidney function in children with CKD and hyperphosphatemia.