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. Materials and Methods: Nine common nonprescription 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, LithoBalance™, and KSP tabs™ contained the most
citrate (means of 63.9, 33.5, and 26.9 mEq, respectively). Moonstone and LithoBalance had the greatest discrepancy between total
citrate and
alkali citrate (15.7 and 11.8 mEq per serving, respectively). NOW®
potassium citrate was least expensive ($0.04/10 mEq
alkali citrate). KSP tabs 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.