[Magnesium hydroxide in idiopathic calcium nephrolithiasis]. / Idrossido di magnesio nella nefrolitiasi calcica idiopatica.

ABSTRACT

BACKGROUND: While in vitro the protective effect of magnesium on calcium oxalate crystallization is well known, its clinical relevance in calcium nephrolithiasis is still debated. Therefore, the clinical and metabolic effects of magnesium hydroxide therapy were evaluated in calcium stone formers. METHODS: Nine patients (7 M, 2 F), selected for a low urinary magnesium excretion (uMg 56 +/- 12 mg/day), were given Mg hydroxide (500 mg/day), with clinical and metabolic controls at 3, 12 and 18 months. RESULTS: Urinary Mg/uCreat increased throughout the study; uOx/uCreat decreased significantly; uCa/uCreat increased but not significantly. The stone recurrence rate decreased from 0.75 to 0.11 stones/year/patient, throughout the study period. The decrease of uOx is considered a more important risk factor in calcium stone patients than a similar uCa change; it may be due to a reduced intestinal Ox absorption, for the formation of insoluble and not absorbed Mg oxalate. CONCLUSION: In conclusion, Mg hydroxide therapy was encouraging in patients with calcium nephrolithiasis and low uMg; nevertheless a longer period of treatment is needed to confirm these data.