Magnésio oral em escolares e adolescentes com fibrose cística: estudo randomizado, duplo-cego, controlado com placebo e cruzado

Abstract

Background: Magnesium (Mg) is one of the most important ions in the body. Although some studies report that patients with cystic fibrosis (CF) lack Mg, no international study has assessed the impact of oral Mg supplementation in CF patients. Objective: We prospectively investigated the long-term effect of oral Mg supplementation on lung function, respiratory muscle strength and Shwachman-Kulczyckis (SK) score of children and adolescents with CF. Design: This double-blind randomized placebo-controlled crossover study included 44 patients with CF (age, 7-19 years; 20 males) who were randomized to receive Mg (n=20, 300mg/day) or placebo (n=20) for 8 weeks with a 4-week washout period between trials. All were undergoing conventional treatment for CF. The experimental protocol included clinical evaluation with SK score, urinary dosage of Mg, manuvacuometry and spirometry. The primary outcome was the forced expiratory volume at first second (FEV1) measured with spirometry. The normality test was performed for all variables. As a crossover design was used and the results were not normally distributed, the Wilcoxon Signed Ranks test was used. In all statistical tests that were used, the difference between groups was significant when the p-value of the test was < 0.05. Results: In spirometry measurements FEV1, the forced vital capacity (FVC) and the FEV1/FVC ratio has augmented significantly in the Mg period only (change in FEV1: 4.17 % predicted after Mg versus 0.72 % predicted after placebo, p=0.002; change in FVC: 3.9 % predicted after Mg versus 0.27 % predicted after placebo, p=0.02; change in FEV1/FVC: 1.73 % predicted after Mg versus -0.99 % predicted after placebo, p=0.002). In respiratory muscle strength measurements, the maximal inspiratory and expiratory pressures (MIP and MEP) significantly improved only after Mg (change in MIP: 11.02% predicted after Mg versus 0.45% predicted after placebo; change in MEP: 11.93% predicted after Mg versus 0.79% predicted after placebo; p < 0.001 for both). Moreover, Mg administration had a beneficial effect on SK score (change: 4.48 points after Mg versus -1.30 points after placebo, p < 0.001). Conclusions: Oral Mg supplementation helped improve lung function, respiratory muscle strength and SK score parameters in children and adolescents with CF evaluated.