"Lemonade therapy appears to have the potential to prevent kidney stones," said Marshall Stoller, MD, professor and vice chairman of urology, University of California, San Francisco, California, who moderated a press briefing at which the research was presented.

Study presenter David Kang, 4^th year medical school student, Duke University Medical Center, Durham, North Carolina, and colleagues compared the urine environment of patients on a lemonade therapy regimen to patients taking potassium citrate.

Kang enrolled 5 men and 7 women in each study arm and measured pre- and post-treatment total volume of urine output and acidity, and levels of calcium, citrate, oxalate, uric acid and sodium. By x-ray and computer-assisted tomography, the stone burden and stone formation rate was also measured.

Eleven of the patients in the 12 lemonade arm improved their urinary citrate levels, changing the level by 354 mg, a difference that was statistically significant from baseline (P <.05). All 12 potassium citrate patients improved their urinary citrate levels an average of 472 mg (P <.05), the difference between the groups was also statistically significant at the P <.05 level.

"Potassium citrate is the preferred treatment for hypocitraturic calcium stone formers," Kang said. However, he acknowledged that lemonade is a good alternative if the patient can't handle the potassium citrate tablets due to adverse effects or cost.

Dr. Stoller noted that, for both products, the level of urinary citrate was well above 600 mg, considered a goal for preventing stone formation.

Kang said that neither group proved that lemonade actually lessened the incidence of clinical stone cases. However, Dr. Stoller said that a larger, long-term study -- advocated by the researchers -- would be likely to show that increasing urinary citrate in these patients would later prove clinical beneficial for prevention of stone formation.

Dr. Stoller said the studies give patients a choice of either the prescription medicine that can be taken in tablets or crystals, or the lemonade.


[Presentation title: Lemonade-Based Dietary Manipulation in Patients With Hypocitraturic Nephrolithiasis. Abstract 1038]

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