LAUSR

OBJECTIVE Potassium citrate effectively decreases kidney stone recurrence, but it is costly and associated with side effects. While several over-the-counter supplements and medical foods purport to provide sufficient citrate to prevent recurrent stones, corroborating data on their actual citrate content is limited. METHODS Nine common non-prescription products were purchased online. Reported citrate content was obtained from packaging, promotional materials, or ingredient labels. Using a single serving of each product, actual citrate, sodium, potassium, calcium, magnesium, and oxalate content was measured using spectrophotometry and chromatography. Total alkali citrate, cost, and amounts of each component per 10 mEq of alkali citrate were also calculated. RESULTS Nearly all products contained more citrate than advertised, except for Litholyte® powder, Litholyte® Coffee, and Horbäach® potassium citrate. Per serving, Moonstone® powder, LithoBalanceTM, and KSP tabsTM contained the most citrate (means of 63.9 mEq, 33.5 mEq, and 26.9 mEq respectively). Moonstone® and LithobalanceTM had the greatest discrepancy between total citrate and alkali citrate (15.7 mEq and 11.8 mEq per serving, respectively). NOW® potassium citrate was least expensive ($0.04/10 mEq alkali citrate). KSP tabsTM delivered the most daily sodium (mean 158 mg/10 mEq alkali citrate, Litholyte® coffee provided the most potassium (mean of 13 mEq/10 mEq alkali citrate), and Kidney COP® provided the most calcium (mean 147 mg/10 mEq alkali citrate). Conclusion Some common over-the-counter products contain sufficient alkali to potentially promote a citraturic response; Moonstone® provides the most alkali citrate, but at a higher cost than other products. Sodium, potassium, and calcium from these products must also be considered in daily consumption.