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Letter to the Editor—Reply

      We thank the author for their interest in our manuscript, and we acknowledge their concerns regarding the potential downstream effects of elevated sodium intake in our alternate alkali (AA) patients. While we agree that the recommendation of a low sodium diet (≤2300 mg daily) is frequently offered to nephrolithiasis patients for conservative dietary management due to concern for the correlation between increased sodium intake and hypercalciuria, the two prospective studies in which low sodium diet was correlated to decreased urine calcium were performed in hypercalciuric patients with elevated baseline 24-hour urine sodium.
      • Borghi L
      • Schianchi T
      • Meschi T
      • et al.
      Comparison of two diets for the prevention of recurrent stones in idiopathic hypercalciuria.
      ,
      • Nouvenne A
      • Meschi T
      • Prati B
      • et al.
      Effects of a low-salt diet on idiopathic hypercalciuria in calcium-oxalate stone formers: a 3-mo randomized controlled trial.
      This is reflected in the AUA Medical Management of Kidney Stones Guidelines which recommend limited sodium intake for patients with calcium stones and relatively high urinary calcium, as well as for patients with cystine stones. As demonstrated in our Table 2, our patient population predominantly had normal urine calcium and sodium, and therefore the administration of sodium bicarbonate (NAB) in these patients did not contradict the guidelines. In fact, the lack of hypercalciuric effect from 60 mEq/day NAB has been demonstrated previously in a prospective RCT.
      • Pinheiro VB
      • Baxmann AC
      • Tiselius HG
      • Heilberg IP
      The effect of sodium bicarbonate upon urinary citrate excretion in calcium stone formers.
      Moreover, there exists some evidence which suggests that sodium supplementation in hypocitraturic patients actually decreases calcium oxalate supersaturation by improving fluid intake and urine volumes.
      • Stoller ML
      • Chi T
      • Eisner BH
      • Shami G
      • Gentle DL
      Changes in urinary stone risk factors in hypocitraturic calcium oxalate stone formers treated with dietary sodium supplementation.
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      References

        • Borghi L
        • Schianchi T
        • Meschi T
        • et al.
        Comparison of two diets for the prevention of recurrent stones in idiopathic hypercalciuria.
        N Engl J Med. 2002; 346: 77-84
        • Nouvenne A
        • Meschi T
        • Prati B
        • et al.
        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; 91: 565-570
        • Pinheiro VB
        • Baxmann AC
        • Tiselius HG
        • Heilberg IP
        The effect of sodium bicarbonate upon urinary citrate excretion in calcium stone formers.
        Urology. 2013; 82: 33-37
        • Stoller ML
        • Chi T
        • Eisner BH
        • Shami G
        • Gentle DL
        Changes in urinary stone risk factors in hypocitraturic calcium oxalate stone formers treated with dietary sodium supplementation.
        J Urol. 2009; 181: 1140-1144
        • Hu MK
        • Witham MD
        • Soiza RL
        Oral bicarbonate therapy in non-haemodialysis dependent chronic kidney disease patients: a systematic review and meta-analysis of randomised controlled trials.
        J Clin Med. 2019; 8: 208-220

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