Patients who have had kidney stones at least once should increase their fluid consumption to produce at least 2 L of urine per day to prevent the condition from recurring, according to new guidelines published by the American College of Physicians.
If increased fluid intake doesn’t prevent recurrent nephrolithiasis, the updated ACP guidelines recommend adding treatment with a thiazide diuretic, citrate, or allopurinol. “Increased fluid intake spread throughout the day can decrease stone recurrence by at least half with virtually no side effects,” said Dr. David A. Fleming, ACP president, in a statement. “However, people who already drink the recommended amount of liquids, or when increased fluid intake is contraindicated, should not increase their fluid intake.”
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Urinating 2 liters or more each day can help stop the return of kidney stones.
The guidelines are based on a review of nephrolithiasis studies, in which the ACP’s director of clinical policy, Dr. Amir Qaseem, and his associates examined baseline stone composition, blood and urine chemistries, and final health outcomes, among other factors. Only English-language trials were used, and research was collected through searches of MEDLINE, the Cochrane Database of Systematic Reviews, Google Scholar, ClinicalTrials.gov, and Web of Science (Ann. Intern. Med. 2014;161:659-67).
Thiazide diuretics, citrates, or allopurinol significantly reduced recurrence of calcium-based stones (the most common type of kidney stone) in patients who had nephrolithiasis at least twice before, according to the analysis.
The ACP guidelines also caution against consuming non-fruit–flavored sodas and carbonated beverages, because they are acidified by phosphoric acid, and dietary animal protein and purines.
However, the guidelines encourage consumption of dietary oxalate – commonly found in chocolate, beets, nuts, rhubarb, spinach, strawberries, tea, and wheat bran – and support maintaining normal dietary calcium. There was no evidence to suggest a risk reduction advantage in drinking tap water rather than mineral water.
The recommendations do not apply to “patients with suspected hyperparathyroidism or other rare cases,” the guidelines authors noted.
Financial support for the guidelines came from the ACP operating budget. The authors had no other relevant financial disclosures.