Oral magnesium supplementation in children with cystic fibrosis improves clinical and functional variables: a double-blind, randomized, placebo-controlled crossover trial.
BACKGROUND
Magnesium is one of the most important minerals in the body. Although some studies reported that patients with cystic fibrosis (CF) lack magnesium, no international study has assessed the importance of oral magnesium supplementation in CF patients.


OBJECTIVE
We prospectively investigated the long-term effect of oral magnesium supplementation on respiratory muscle strength by using manuvacuometry and the Shwachman-Kulczycki (SK) score among children and adolescents with CF.


METHODS
This double-blind, randomized, placebo-controlled crossover study included 44 CF patients (aged 7-19 y; 20 males) who were randomly assigned to receive magnesium (n = 22; 300 mg/d) or placebo (n = 22) for 8 wk with a 4-wk washout period between trials. All patients were undergoing conventional treatment of CF. The experimental protocol included clinical evaluation, assessment of urinary concentration of magnesium, and manuvacuometric measurements [maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP)]. MIP was the primary outcome.


RESULTS
Urinary magnesium increased after the administration of magnesium (change: 36.38 mg/d after magnesium compared with 0.72 mg/d after placebo; P < 0.001). Moreover, MIP and MEP significantly improved only after magnesium administration (change in MIP: 11% predicted after magnesium compared with 0.5% predicted after placebo; change in MEP: 11.9% predicted after magnesium compared with 0.8% predicted after placebo; P < 0.001 for both). Magnesium administration had a beneficial effect on clinical variables assessed by the SK score (change: 4.48 points after magnesium compared with -1.30 points after placebo; P < 0.001).


CONCLUSIONS
Oral magnesium supplementation helped improve both the SK score and respiratory muscle strength in pediatric patients with CF.
Pediatrics Department, Diagnostic Support Action and Research Center (NUPAD), Faculty of Medicine, Federal University of Minas Gerais, Belo Horizonte, Brazil. clesiogontijo@gmail.com
Clésio
C
Gontijo-Amaral
Elizabet V
EV
Guimarães
Paulo
P
Camargos
D000293:Adolescent; D000328:Adult; D002648:Child; D018592:Cross-Over Studies; D003550:Cystic Fibrosis / Q000178:diet therapy* / Q000503:physiopathology / Q000652:urine; D019587:Dietary Supplements / Q000032:analysis; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D005998:Glycine / Q000008:administration & dosage; D006801:Humans; D008274:Magnesium / Q000627:therapeutic use* / Q000652:urine; D008297:Male; D053580:Muscle Strength; D009942:Organometallic Compounds / Q000008:administration & dosage; D012129:Respiratory Function Tests; D012132:Respiratory Muscles / Q000503:physiopathology; D012720:Severity of Illness Index; D055815:Young Adult
D009942:Organometallic Compounds; D008274:Magnesium; D005998:Glycine