Effects of a low-salt diet on idiopathic hypercalciuria in calcium-oxalate stone formers: a 3-mo randomized controlled trial

Am J Clin Nutr. 2010 Mar;91(3):565-70. doi: 10.3945/ajcn.2009.28614. Epub 2009 Dec 30.


Background: A direct relation exists between sodium and calcium excretion, but randomized studies evaluating the sustained effect of a low-salt diet on idiopathic hypercalciuria, one of the main risk factors for calcium-oxalate stone formation, are still lacking.

Objective: Our goal was to evaluate the effect of a low-salt diet on urinary calcium excretion in patients affected by idiopathic calcium nephrolithiasis.

Design: Patients affected by idiopathic calcium stone disease and hypercalciuria (>300 mg Ca/d in men and >250 mg Ca/d in women) were randomly assigned to receive either water therapy alone (control diet) or water therapy and a low-salt diet (low-sodium diet) for 3 mo. Twenty-four-hour urine samples were obtained twice from all patients: one sample at baseline on a free diet and one sample after 3 mo of treatment.

Results: A total of 210 patients were randomly assigned to receive a control diet (n = 102) or a low-sodium diet (n = 108); 13 patients (2 on the control diet, 11 on the low-sodium diet) withdrew from the trial. At the follow-up visit, patients on the low-sodium diet had lower urinary sodium (mean +/- SD: 68 +/- 43 mmol/d at 3 mo compared with 228 +/- 57 mmol/d at baseline; P < 0.001). Concomitant with this change, they showed lower urinary calcium (271 +/- 86 mg/d at 3 mo compared with 361 +/- 129 mg/d on the control diet, P < 0.001) and lower oxalate excretion (28 +/- 8 mg/d at 3 mo compared with 32 +/- 10 mg/d on the control diet, P = 0.001). Urinary calcium was within the normal range in 61.9% of the patients on the low-salt diet and in 34.0% of those on the control diet (difference: +27.9%; 95% CI: +14.4%, +41.3%; P < 0.001).

Conclusion: A low-salt diet can reduce calcium excretion in hypercalciuric stone formers. This trial was registered at clinicaltrials.gov as NCT01005082.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Calcium / urine*
  • Calcium Oxalate / metabolism*
  • Diet, Sodium-Restricted*
  • Female
  • Humans
  • Hypercalciuria / diet therapy*
  • Hypercalciuria / urine
  • Kidney Calculi / chemistry
  • Kidney Calculi / diet therapy*
  • Kidney Calculi / urine
  • Male
  • Middle Aged
  • Sodium / urine*
  • Sodium Chloride, Dietary / urine*
  • Water


  • Sodium Chloride, Dietary
  • Water
  • Calcium Oxalate
  • Sodium
  • Calcium

Associated data

  • ClinicalTrials.gov/NCT01005082