How to manage nephrolithiasis?

Management of Nephrolithiasis

Increased fluid intake to achieve at least 2 L of urine per day is the cornerstone of nephrolithiasis management, followed by pharmacologic therapy with thiazide diuretics, citrate, or allopurinol when increased fluid intake fails to reduce stone formation. 1, 2

First-Line Management: Fluid Intake and Dietary Modifications

Fluid Intake

• Increase fluid intake to achieve urine volume >2.5 L/day 2, 3
• Spread fluid intake throughout the day and night to maintain consistent urine dilution 3
• Water is the preferred fluid, with some evidence supporting coffee, tea, wine, and orange juice 2
• Avoid sugar-sweetened beverages and those acidified with phosphoric acid (e.g., colas) 1, 2

Dietary Modifications

• Maintain normal dietary calcium intake (1,000-1,200 mg/day) 2
• Limit sodium intake to <2,300 mg/day 2
• Limit animal protein intake to 5-7 servings of meat, fish, or poultry per week 2
• Reduce purine intake for patients with hyperuricosuria 2

Pharmacologic Management

When increased fluid intake fails to prevent recurrent stone formation, consider pharmacologic therapy based on stone type and metabolic abnormalities:

For Calcium Stones

1. Thiazide Diuretics (for hypercalciuria):

   • Hydrochlorothiazide 25mg twice daily
   • Chlorthalidone 25mg daily
   • Indapamide 2.5mg daily 1, 2
   • Note: Higher doses of thiazides are associated with more adverse effects 1

2. Potassium Citrate (for hypocitraturia or low urinary pH):

   • Dosage: 30-80 mEq daily in 3-4 divided doses 2
   • Target urinary citrate: 400-700 mg/day
   • Target urinary pH: 6.2-6.5 2

For Uric Acid Stones

1. Potassium Citrate (first-line):

   • Goal: Increase urinary pH to 6.0 2
   • Dosage: 30-80 mEq daily in 3-4 divided doses 2

2. Allopurinol (second-line):

   • Not recommended as first-line therapy for uric acid stones 2
   • Consider for hyperuricosuria with calcium oxalate stones 2, 4
   • Dosage adjustment required in renal impairment 4

For Cystine Stones

• Potassium Citrate:
  • Goal: Increase urinary pH to 7.0 2
  • Dosage: 30-80 mEq daily in 3-4 divided doses 2

Monitoring and Follow-up

• Obtain 24-hour urine specimen within 6 months of starting treatment 2
• Regular urinalysis to assess for crystalluria 2
• Monitor serum uric acid levels when using allopurinol 4
• For patients on thiazides, monitor electrolytes and consider potassium supplementation 2
• Adjust medication doses based on urinary parameters and clinical response 2

Management of Complicated Nephrolithiasis

Infection-Associated Stones

• Complete eradication of stones with percutaneous nephrolithotomy or extracorporeal shock wave lithotripsy 5
• Prompt drainage of collecting system if obstruction is present 5
• Careful selection of antimicrobial therapy, especially in severe sepsis 5

Stone Size and Location-Based Treatment

For stones requiring procedural intervention, consider:

• <10 mm stones in renal pelvis or upper/middle calyx: ESWL or flexible URS
• 10-20 mm stones in renal pelvis or upper/middle calyx: ESWL or flexible URS
• <10 mm stones in lower pole: Flexible URS or ESWL
• 10-20 mm stones in lower pole: Flexible URS or PCNL

• 20 mm stones in any location: PCNL 2

Common Pitfalls to Avoid

• Restricting dietary calcium (may increase stone risk) 2
• Using sodium citrate instead of potassium citrate (sodium load may increase urine calcium excretion) 2
• Neglecting follow-up monitoring 2
• Failing to address underlying metabolic disorders 2
• Using allopurinol as first-line for uric acid stones (urinary alkalinization is more effective) 2, 4
• Inadequate hydration during nighttime (leads to concentrated urine) 3

By following this comprehensive approach to nephrolithiasis management, focusing first on increased fluid intake and dietary modifications, followed by targeted pharmacologic therapy based on stone type and metabolic abnormalities, recurrent stone formation can be significantly reduced.