What are the medical treatments for all types of kidney stones?

Medical Treatment of Kidney Stones

The most effective medical treatment for kidney stones requires a combination of high fluid intake, targeted dietary modifications, and specific pharmacotherapy based on stone composition, with thiazide diuretics, potassium citrate, and allopurinol being the primary medication options for different stone types. 1

General Treatment Principles

Fluid Intake

• Increase fluid intake to achieve urine output of at least 2 liters per day 1
• For cystine stones: higher target of at least 3-4 liters per day to maintain urinary cystine concentration below 250 mg/L 1, 2
• Distribute fluid intake throughout the day, including two glasses with each meal and before bedtime 2
• Water is the preferred fluid, though some evidence suggests coffee, tea, and certain beverages may also be beneficial 3, 4

Treatment by Stone Type

Calcium Stones (Calcium Oxalate and Calcium Phosphate)

Dietary Management:

• Maintain normal calcium intake (1000-1200 mg/day) rather than restricting calcium 1, 3
• Restrict sodium intake to 2300 mg/day or less 1, 5
• Limit oxalate-rich foods in patients with hyperoxaluria 1, 3
• Consume calcium-containing foods with meals to bind dietary oxalate 1
• Increase fruit and vegetable intake to increase urinary citrate 3

Pharmacologic Treatment:

1. Thiazide Diuretics for hypercalciuria:

   • Hydrochlorothiazide 25 mg twice daily or 50 mg once daily
   • Chlorthalidone 25 mg once daily
   • Indapamide 2.5 mg once daily 1
   • Continue dietary sodium restriction to maximize hypocalciuric effect 1
   • Monitor for hypokalemia and glucose intolerance 1

2. Potassium Citrate for hypocitraturia:

   • For patients with low urinary citrate or low urinary pH 1
   • Potassium citrate preferred over sodium citrate (which may increase urinary calcium) 1
   • Effective for both calcium oxalate and calcium phosphate stones 1, 6

3. Allopurinol for hyperuricosuria:

   • For patients with recurrent calcium oxalate stones with hyperuricosuria (>800 mg/day) and normal urinary calcium 1
   • Not indicated based on hyperuricemia alone 1

Uric Acid Stones

Dietary Management:

• Limit animal protein intake to 0.8-1.0 g/kg/day 5, 3
• Increase fluid intake to achieve >2 liters urine output 6

Pharmacologic Treatment:

1. Potassium Citrate (first-line therapy):

   • Target urinary pH of 6.0 1
   • Addresses the primary issue of low urinary pH 1, 6

2. Allopurinol:

   • Not recommended as first-line therapy 1
   • Consider only if alkalinization is insufficient and hyperuricosuria is present 1, 6

Cystine Stones

Dietary Management:

• Extremely high fluid intake (>4 liters/day) to achieve urine output >3 liters 1, 2
• Restrict sodium intake to ≤2300 mg/day 1
• Limit animal protein intake 1

Pharmacologic Treatment:

1. Potassium Citrate:

   • Target urinary pH of 7.0 1
   • First-line pharmacologic therapy 1, 6

2. Cystine-binding Thiol Drugs (second-line):

   • Tiopronin (alpha-mercaptopropionylglycine) for patients unresponsive to conservative measures 1, 2
   • Starting dose: 800 mg/day in adults; 15 mg/kg/day in children 2
   • Adjust dose based on urinary cystine levels measured at 1 month and every 3 months thereafter 2
   • Preferred over d-penicillamine due to better side effect profile 1, 2

Struvite Stones (Infection Stones)

• Complete surgical removal of stones when possible 6
• Appropriate antibiotic therapy for underlying infection 6
• Acetohydroxamic acid (AHA) may be beneficial but has extensive side effects 1

Monitoring and Follow-up

• Obtain 24-hour urine specimen within 6 months of initiating treatment 1
• Repeat 24-hour urine specimen annually or more frequently based on stone activity 1
• Monitor blood tests periodically for medication side effects:
  • Thiazides: potassium and glucose levels
  • Allopurinol and tiopronin: liver enzymes
  • Potassium citrate: potassium levels 1
• Obtain repeat stone analysis when available, especially in patients not responding to treatment 1

Common Pitfalls to Avoid

1. Calcium restriction - may paradoxically increase stone risk by increasing oxalate absorption 1, 3
2. Using sodium citrate instead of potassium citrate - can increase urinary calcium excretion 1
3. Prescribing allopurinol as first-line therapy for uric acid stones - urinary alkalinization is more effective 1
4. Inadequate fluid intake - the most important preventive measure for all stone types 1, 4
5. Failure to monitor for medication side effects - especially important with thiol drugs and thiazides 1
6. Not adjusting treatment based on stone composition - different stone types require different approaches 1, 6

By following these evidence-based guidelines, the risk of kidney stone recurrence can be significantly reduced, improving patient morbidity and quality of life.