What are the recommendations for preventing repeat kidney stones?

Recommendations for Preventing Recurrent Kidney Stones

The most effective strategy to prevent recurrent kidney stones is to increase fluid intake to achieve at least 2 liters of urine output per day, which can reduce stone recurrence by more than 50%. 1, 2

First-Line Dietary Interventions

• Increase fluid intake throughout the day to achieve at least 2 liters of urine output daily, which reduces composite stone recurrence from 27% to 12.1% 1, 3
• Reduce consumption of soft drinks acidified by phosphoric acid (typically colas), which has been shown to decrease stone recurrence from 45.6% to 29.7% 1, 2
• Maintain normal to high dietary calcium intake (1000-1200 mg/day) rather than restricting it, as low-calcium diets are associated with higher stone recurrence (38.3% vs 20.0% with normal/high calcium) 1, 2, 3
• Limit sodium intake to reduce urinary calcium excretion 2, 3
• Limit animal protein consumption to 0.8-1.0 g/kg body weight/day 2, 3
• Increase consumption of citrus fruits which naturally contain citrate 2, 3

When to Consider Pharmacological Interventions

When increased fluid intake fails to prevent stone formation, pharmacological therapy should be initiated 1, 2:

• Thiazide diuretics: Effective for calcium stones, particularly in patients with hypercalciuria 1, 2, 4
• Potassium citrate: Recommended for patients with hypocitraturia or those forming calcium stones 1, 2, 4
• Allopurinol: Beneficial for patients with hyperuricosuria or uric acid stones 1, 2, 4

Stone-Specific Prevention Strategies

For Calcium Stones (most common)

• Increase fluid intake to achieve 2L urine output daily 1, 2
• Consider thiazide diuretics for hypercalciuria 1, 2, 5
• Consider potassium citrate for hypocitraturia 1, 2, 4
• Maintain normal dietary calcium intake 1, 2
• Limit sodium and animal protein consumption 2, 3

For Uric Acid Stones

• Increase fluid intake to achieve 2L urine output daily 1, 2
• Consider allopurinol for hyperuricosuria 1, 2, 5
• Alkalinize urine with potassium citrate 2, 4, 5
• Limit purine-rich foods 3, 5

Common Pitfalls to Avoid

• Calcium restriction: Contrary to intuition, low calcium diets can increase stone formation by allowing more oxalate absorption 1, 2
• Inadequate hydration monitoring: Simply recommending increased fluid intake without specific targets often fails; aim for 2.5-3.0 L/day fluid intake to achieve >2 L urine output 3, 6
• Overreliance on fruit juices: While citrus juices can increase citrate, some juices are high in oxalate which may increase stone risk 2, 7
• Ignoring medication side effects: Higher doses of thiazides are more effective but have more adverse effects 8, 5
• Vitamin supplementation: Excessive vitamin C and vitamin D supplements may increase stone risk 3, 9

Implementation Strategies

• Use a connected water bottle or mobile app to track fluid intake throughout the day 6
• Distribute fluid intake throughout the day rather than consuming large volumes at once 2, 7
• Compensate with additional fluids when working in high-temperature environments or after exercise 3, 7
• Consider using potassium citrate as monotherapy rather than combination therapy, as evidence suggests combination therapy is not more beneficial 1, 8

While biochemical testing and stone analysis are commonly used in clinical practice, randomized controlled trial evidence supporting treatment selection based on these parameters is limited 1, 2, 8. Nevertheless, the American College of Physicians recommends a tailored approach based on stone composition when available 2, 8.