Comparing Alkalinizing Agents Efficacy on Stone Risk in Patients on a Metabolically Controlled Diet

Kidney stones are a common medical problem, occurring in almost 10% of people in the United States1. Furthermore, 50% of patients will recur within 10 years2. Metabolic testing is advised in recurrent stone formers, as well as those considered high risk, to assess for a specific abnormality which may prompt intervention to prevent future stone formation. Non-surgical interventions include both dietary counselling, as well as pharmacotherapy.

One of the most commonly prescribed class of pharmacotherapies is alkali therapy which can be used to both increase the urinary pH and raise the urine citrate levels. This is particularly useful as correction of very acidic urinary pH (<5.5) can counteract uric acid crystallization thereby preventing or even dissolving uric acid stones3. Further, citrate has been shown to be a potent inhibitor of calcium stones by binding to the calcium directly4 and inhibiting crystal nucleation, thereby reducing calcium stone formation5,6.

The most commonly utilized preparation of alkali therapy is potassium citrate which has been shown to prevent stone formation better than sodium citrate7. Unfortunately, some forms of potassium citrate (crystal packets) have become unavailable, and the slow release form of potassium citrate (UroCit-K) now exceeds $15/day in cost8. There have been multiple alternative alkali therapies that have been used in place of potassium citrate, including both medical foods and prescription medications, but with little evidence to support their use. A pilot study in order to quantify the metabolic effects of these agents and compare them to potassium citrate will be performed.