What are the methods for preventing nephrolithiasis (kidney stones)?

From the Guidelines

To prevent nephrolithiasis, increasing fluid intake to achieve at least 2 L of urine per day is the most effective method, as recommended by the American College of Physicians 1. This approach is supported by the evidence that higher fluid intake reduces the risk of stone formation, as demonstrated by observational studies and a randomized controlled trial 1.

Key Recommendations

• Increase fluid intake to achieve at least 2 L of urine per day, which can be tailored to the individual patient by using the information on total volume from the 24 h urine collections 1.
• Dietary changes, such as reducing dietary oxalate, reducing dietary animal protein, and maintaining normal dietary calcium, can also help prevent recurrent kidney stones 1.
• For patients with active disease in which increased fluid intake fails to reduce the formation of stones, pharmacologic monotherapy with a thiazide diuretic, citrate, or allopurinol may be recommended 1.

Rationale

The goal of preventing nephrolithiasis is to decrease the concentrations of lithogenic factors and increase the concentrations of inhibitors of stone formation.

• Increasing fluid intake helps to dilute the urine and reduce the concentration of stone-forming substances.
• Dietary changes, such as reducing dietary oxalate and animal protein, can help reduce the concentration of lithogenic factors.
• Pharmacologic interventions, such as thiazide diuretics and citrate, can help adjust urine pH and mineral concentrations to inhibit stone development.

Important Considerations

• The American College of Physicians recommends a weak recommendation, low-quality evidence for increasing fluid intake to prevent recurrent nephrolithiasis 1.
• The evidence for pharmacologic interventions is moderate-quality, but still a weak recommendation 1.
• It is essential to tailor the recommendation to the individual patient, taking into account their specific needs and medical history.

From the FDA Drug Label

The main inclusion criterion was a history of stone passage or surgical removal of stones during the 3 years prior to initiation of Potassium Citrate therapy. All patients began alkali treatment with 60-80 mEq Potassium Citrate daily in 3 or 4 divided doses Throughout treatment, patients were instructed to stay on a sodium restricted diet (100 mEq/day) and to reduce oxalate intake (limited intake of nuts, dark roughage, chocolate and tea). A moderate calcium restriction (400-800 mg/day) was imposed on patients with hypercalciuria

• Methods for preventing nephrolithiasis (kidney stones) include:
  • Sodium restricted diet (100 mEq/day)
  • Reducing oxalate intake (limited intake of nuts, dark roughage, chocolate and tea)
  • Moderate calcium restriction (400-800 mg/day) for patients with hypercalciuria
  • Potassium Citrate therapy to increase urinary citrate excretion and urinary pH 2

From the Research

Methods for Preventing Nephrolithiasis

The following methods can help prevent nephrolithiasis (kidney stones):

• Increase urine volume by increasing oral intake of fluids, especially water, to lower supersaturation of salts and reduce the risk of precipitation 3
• Consume a diet rich in fruits and vegetables, low in animal proteins and salt, with balanced dairy product consumption, and high fluid intake 4
• Limit sodium intake to reduce urinary calcium excretion and stone risk 4, 5, 6
• Maintain a balanced consumption of calcium (≥ 1 g/day) to reduce the risk of stone formation in hypercalciuric stone forming adults 4, 5, 6
• Restrict dietary oxalate intake, especially in patients with known elevated consumption, and maintain a normal to high calcium intake (800-1200 mg/day) to reduce urinary excretion of oxalate 6
• Increase intake of citrate-rich foods, such as citrus fruits and non-citrus fruits, to raise urine citrate levels and protect against stone formation 6
• Limit protein intake to decrease calciuria and reduce the risk of stone formation 5, 6
• Avoid soft drinks and limit caffeine and chocolate consumption, as they may increase the risk of stone events 4, 7

Dietary Recommendations

Dietary recommendations for preventing kidney stones include:

• A vegetarian or Mediterranean diet, which is rich in fruits and vegetables, low in animal proteins and salt, and high in fluid intake 4
• A diet low in oxalate and high in calcium to reduce urinary excretion of oxalate 6
• A diet rich in citrate, such as citrus fruits and non-citrus fruits, to raise urine citrate levels and protect against stone formation 6
• A low-protein, low-salt diet with high hydration (> 3 liters/day) in children with cystinuria 6
• A diet rich in calcium (1200 mg/day) and low in animal protein, with high intake of plant products, to maintain skeletal wellness and prevent kidney stones in older patients 6

Fluid Intake

Fluid intake is essential for preventing kidney stones, with recommendations including:

• Drinking at least 2 liters of water per day to achieve a daily urine output of 2 liters 3, 6
• Increasing fluid intake to reduce stone formation, with higher fluid intake associated with increased urine output and reduced stone formation 7
• Avoiding fluids low in calcium, as they may increase the risk of kidney stone formation 7