Medical management of stone disease

Dietary manipulation still remains one of the most important strategies for therapy. A growing body of evidence, however, suggests that severe calcium restriction is inappropriate in patients with recurrent nephrolithiasis. Dietary recommendations based on recent evidence and the role of bacteria in the pathogenesis of calcium nephrolithiasis are discussed.

New evidence strongly supports the role of oxalate, salt and animal protein dietary restrictions in the prevention of calcium stone recurrence. Moderate calcium restriction is only effective in absorptive hypercalciuria. Calcium restriction is not effective in other etiologies of calcium stones and its implementation can lead to bone demineralization. New evidence has implicated the lack of intestinal bacteria to be responsible for the degradation of dietary oxalate, with its higher absorption resulting in an increased risk of calcium oxalate stone formation. The role of Oxalobacter formigenes is herein discussed.

Metabolic abnormalities responsible for stone recurrence are currently identified in 97% of evaluated patients and remission rates of medical prophylaxis in calcium stone formers are approaching 80%. Urinary calcium excretion in most renal stone formers is more dependent on the dietary acid load than on the dietary calcium intake itself. Reducing the acid-ash content of the diet has an impact on decreasing stone recurrence, while preventing bone loss. New evidence associates the decolonization of oxalate degrading intestinal flora with a higher risk of calcium oxalate stone formation, possibly opening the door for biological manipulation as a novel approach for the prevention of urinary stone formation.