What is the treatment for nephrolithiasis (kidney stones)?

Treatment of Nephrolithiasis (Kidney Stones)

The first-line treatment for nephrolithiasis is increased fluid intake to achieve at least 2 liters of urine output per day, with pharmacologic therapy (thiazide diuretics, citrate, or allopurinol) recommended when fluid therapy fails to prevent stone recurrence. 1, 2

Non-Pharmacological Management

Fluid Intake

• Increased fluid intake to achieve at least 2-2.5 L of urine output daily is the cornerstone of treatment for preventing kidney stone recurrence 1, 2, 3
• Fluid intake should be balanced between day and night to avoid urinary supersaturation during nighttime 3
• Water is the preferred fluid, with no significant difference between tap water and mineral water 2
• A high fluid intake reduces stone recurrence risk by approximately 50% compared to no treatment 1

Dietary Modifications

• Reduce consumption of soft drinks acidified by phosphoric acid (colas) 2, 1
• Maintain normal dietary calcium intake rather than restricting it, as calcium restriction may actually increase stone risk 2, 4
• Moderate dietary salt restriction helps limit urinary calcium excretion 4
• Low-normal protein intake decreases calciuria and could be useful in stone prevention 4
• Increased intake of fruits and vegetables (except those high in oxalate) increases citrate excretion and provides protection against stone formation 4

Pharmacological Management

When increased fluid intake fails to prevent stone formation, pharmacologic therapy should be initiated based on stone type and metabolic abnormalities:

For Calcium Stones (80% of all kidney stones)

• Thiazide diuretics (e.g., hydrochlorothiazide, chlorthalidone, indapamide) reduce calcium stone recurrence by approximately 50% and are particularly beneficial for patients with hypercalciuria 1, 2, 5
• Citrate therapy (potassium citrate) reduces calcium stone recurrence by about 75% by binding to calcium and decreasing urine acidity 1, 2
• Allopurinol reduces stone recurrence by approximately 40% and is most beneficial for patients with hyperuricemia or hyperuricosuria 1, 2

For Uric Acid Stones

• Allopurinol is recommended for patients with hyperuricosuria 5, 4
• Potassium citrate to alkalinize urine 5

Treatment Algorithm

1. First-line treatment for all stone types:

   • Increase fluid intake to achieve at least 2 L of urine output daily 1, 2
   • Implement appropriate dietary modifications based on stone type 2, 4

2. If fluid therapy fails (continued stone formation):

   • For calcium stones with hypercalciuria: Thiazide diuretic 1, 2
   • For calcium stones with hypocitraturia: Potassium citrate 2, 5
   • For calcium stones with hyperuricosuria: Allopurinol 1, 2
   • For uric acid stones: Allopurinol and potassium citrate 5, 4

Important Considerations

• Monotherapy is generally as effective as combination therapy for preventing stone recurrence 2
• Higher doses of thiazides are associated with more adverse effects but have better-established effectiveness in preventing stone recurrence than lower doses 5
• A randomized prospective 5-year study showed that high water intake alone reduced recurrence rates from 27% to 12% and extended the average time to recurrence from 25 months to 39 months 6
• Although biochemical testing is commonly used to guide treatment selection, randomized controlled trial evidence supporting this approach is limited 2, 5
• Patient compliance with increased fluid intake can be challenging and requires practical strategies and daily routines to ensure adequate hydration 3