What is the treatment and management for nephrolithiasis (kidney stones)?

Treatment and Management of Nephrolithiasis (Kidney Stones)

Increased fluid intake to achieve at least 2 liters of urine output daily is the first-line treatment for preventing kidney stone formation and recurrence. 1, 2, 3

Non-Pharmacological Management

Fluid Intake

• Increase fluid intake to achieve at least 2-2.5 liters of urine output per day as the cornerstone of prevention 1, 2, 4
• Balance fluid intake between day and night to avoid urinary supersaturation during nighttime 4
• Water is the preferred fluid of choice, with no significant difference between tap water and mineral water 1, 5
• Certain beverages like coffee, tea, wine, and orange juice may be associated with lower risk of stone formation 2
• Avoid sugar-sweetened beverages and soft drinks acidified by phosphoric acid (colas) as they may increase stone risk 1, 2

Dietary Modifications

• Maintain normal dietary calcium intake of 1,000-1,200 mg per day rather than restricting it, as calcium restriction can paradoxically increase stone risk by increasing urinary oxalate 2, 6
• Consume calcium primarily with meals to enhance gastrointestinal binding of oxalate 2
• Limit sodium intake to 2,300 mg daily to reduce urinary calcium excretion 2, 6
• Reduce consumption of animal protein, which generates sulfuric acid that increases urinary calcium and reduces urinary citrate 2, 6
• Limit dietary oxalate for patients with oxalate stones, avoiding foods like certain nuts, vegetables, wheat bran, chocolate, and tea 2, 6
• Increase potassium intake through fruits and vegetables to increase urinary citrate excretion 2, 6
• Limit vitamin C supplements as vitamin C can be metabolized to oxalate 2

Pharmacological Management

When to Initiate Pharmacotherapy

• Offer pharmacologic therapy when increased fluid intake fails to reduce stone formation 7, 1, 2

Medication Selection Based on Stone Type and Metabolic Abnormalities

For Calcium Stones

• Thiazide diuretics (hydrochlorothiazide, chlorthalidone, indapamide) for patients with hypercalciuria 1, 2, 3
• Potassium citrate for patients with hypocitraturia or low urinary pH 1, 2, 8
• Allopurinol for patients with hyperuricosuria and normal urinary calcium 1, 2

For Uric Acid Stones

• Potassium citrate to increase urinary pH to 6.0-7.0 8
• Allopurinol for patients with hyperuricosuria 2, 8

Dosing Guidelines for Potassium Citrate

• For severe hypocitraturia (urinary citrate <150 mg/day): Start at 60 mEq/day (30 mEq twice daily or 20 mEq three times daily) 8
• For mild to moderate hypocitraturia (urinary citrate >150 mg/day): Start at 30 mEq/day (15 mEq twice daily or 10 mEq three times daily) 8
• Take with meals or within 30 minutes after meals or bedtime snack 8
• Avoid doses greater than 100 mEq/day 8
• Monitor serum electrolytes, creatinine, and complete blood counts every four months 8

Treatment Algorithm Based on Stone Type

Calcium Oxalate/Phosphate Stones (80% of all stones)

1. First-line: Increase fluid intake to achieve 2L urine output daily 1, 2, 3
2. Second-line (if fluid therapy fails):
   • For hypercalciuria: Thiazide diuretics 1, 2
   • For hypocitraturia: Potassium citrate 1, 2, 8
   • For hyperuricosuria: Allopurinol 1, 2

Uric Acid Stones

1. First-line: Increase fluid intake to achieve 2L urine output daily 1, 3
2. Second-line:
   • Potassium citrate to alkalinize urine (target pH 6.2-6.5) 8
   • Allopurinol for hyperuricosuria 2, 8

Infection (Struvite) Stones

• Treat underlying urinary tract infection with appropriate antibiotics 9
• Complete surgical eradication of stones is often necessary 9
• Increase fluid intake to achieve 2L urine output daily 1, 4

Monitoring and Follow-up

• Obtain 24-hour urine collections to assess metabolic abnormalities and guide therapy 2
• Measure parameters including volume, pH, calcium, oxalate, uric acid, citrate, sodium, potassium, and creatinine 2
• Monitor urinary citrate and/or pH every four months to evaluate treatment effectiveness 8
• For patients on potassium citrate, monitor serum electrolytes, creatinine, and complete blood counts every four months 8

Common Pitfalls to Avoid

• Restricting dietary calcium, which can paradoxically increase stone risk by increasing urinary oxalate 2, 6
• Using sodium citrate instead of potassium citrate, as the sodium load can increase urinary calcium 2
• Overreliance on calcium supplements rather than dietary calcium sources 2
• Inadequate fluid intake, especially during periods of increased fluid loss (exercise, hot weather) 4, 6
• Delaying treatment of urinary tract infections in patients with stones, which can lead to sepsis in obstructed systems 9