ACP: New Guidelines Address Recurring Kidney Stones

Drinking more fluids—enough to produce 2 L of urine a day—could decrease recurrence of kidney stones by 50%, according to new guidelines issued by the American College of Physicians.

The guidelines, based on literature published through March 2014, deals specifically with nephrolithiasis—in which kidney stones develop within the urinary tract due to high concentrations of crystal-forming substances. Without treatment, nephrolithiasis reoccurs in 30% to 50% of patients.

Prevention of nephrolithiasis recurrence focuses on an effort to reduce dietary oxalate, a key factor in crystal formation. Dietary changes include increased water intake and reduced dietary protein.

After conducting a systematic evidence review, researchers were able to form the following recommendations:

• Increase fluid intake spread throughout the day to achieve at least 2 L of urine per day to prevent recurrent nephrolithiasis. (Grade: weak recommendation, low-quality evidence)

• Pharmacologic monotherapy with a thiazide diuretic, citrate, or allopurinol to prevent recurrent nephrolithiasis in patients with active disease in which increased fluid intake fails to reduce the formation of stones. (Grade: weak recommendation, moderate-quality evidence)

Of the dietary changes studied, increased water intake and decreased soft drink (specifically colas, which are acidified with phosphoric acid rather than citric acid) intake showed the most significant decreases in recurrence. Evidence regarding increased mineral water and fiber intake, and decreased animal protein intake, was inconclusive.

The full guidelines were published in Annals of Internal Medicine.

—Michael Potts

Reference:

Qaseem A, Dallas P, Forciea MA, et al. Dietary and pharmacologic management to prevent recurrent nephrolithiasis in adults: a clinical practice guideline from the American College of Physicians. Ann Intern Med. 2014;161(9):659-667.