What are the treatment options for a patient presenting with kidney stones, including dietary changes and medication management?

Treatment of Kidney Stones

All patients with kidney stones should immediately increase fluid intake to achieve at least 2 liters of urine output daily, and if dietary measures fail to prevent recurrence, initiate pharmacologic monotherapy with thiazide diuretics, potassium citrate, or allopurinol based on the specific metabolic abnormality. 1

Initial Dietary Management (First-Line for All Patients)

Fluid intake is the cornerstone of both acute and preventive management:

• Increase fluid intake throughout the day to produce at least 2-2.5 liters of urine daily - this reduces stone recurrence by approximately 50% with no reported side effects 1, 2
• Water, coffee, tea, beer, and wine reduce stone formation risk and should be encouraged 2, 3
• Avoid grapefruit juice (increases stone risk by 40%), sugar-sweetened beverages, and colas acidified with phosphoric acid 1, 2
• Orange juice has no protective effect despite common belief 2

Additional dietary modifications for calcium stone formers (80% of cases):

• Maintain normal dietary calcium intake of 1,000-1,200 mg/day - do not restrict calcium as this paradoxically increases intestinal oxalate absorption 2, 4
• Restrict dietary sodium to ≤2,300 mg/day (approximately 3-5 g of sodium chloride) 2, 4
• Reduce animal protein to 0.8-1.0 g/kg body weight/day (approximately 5-7 servings of meat, fish, or poultry per week) 2, 4
• Increase fruits and vegetables to counterbalance acid load 2
• Reduce oxalate-rich foods in patients with absorptive hyperoxaluria 4, 5

Pharmacologic Management (When Dietary Measures Fail)

The American College of Physicians recommends pharmacologic monotherapy as second-line therapy when increased fluid intake fails to prevent stone recurrence. 1 Selection depends on the metabolic abnormality:

For Hypercalciuria (>200 mg/day urinary calcium):

• Thiazide diuretics are first-line therapy 1, 2, 6
• Hydrochlorothiazide 25 mg twice daily or 50 mg once daily 7
• Thiazides lower urinary calcium excretion and reduce stone recurrence 1, 5

For Hypocitraturia (<320 mg/day urinary citrate):

• Potassium citrate 30-100 mEq/day is first-line therapy 2, 6, 5
• Target urinary pH of 6.0-6.5; do not exceed pH 7.0 to avoid calcium phosphate precipitation 2
• Potassium citrate is preferred over sodium citrate because sodium increases urinary calcium excretion 6

For Hyperuricosuria (>800 mg/day in men, >750 mg/day in women) with normocalciuria:

• Allopurinol is recommended 1, 2, 5
• Start with 100 mg daily and increase weekly by 100 mg until serum uric acid ≤6 mg/dL, not exceeding maximum recommended dosage 8
• Maintain fluid intake sufficient to yield at least 2 liters of daily urinary output to avoid xanthine calculi formation 8
• Maintain neutral or slightly alkaline urine 8

For Uric Acid Stones:

• Potassium citrate is first-line therapy (not allopurinol) to raise urinary pH to approximately 6.0-7.2 6, 7
• Oral chemolysis with alkalinization using citrate or sodium bicarbonate 7

For Cystine Stones:

• First-line therapy includes increased fluid intake, sodium and protein restriction, and urinary alkalinization 6
• Tiopronin can be used if alkalinization and adequate fluid intake are insufficient 5

For Brushite (Calcium Phosphate) Stones:

• Potassium citrate for hypocitraturia or elevated urine pH 6
• Thiazide diuretics for hypercalciuria 6
• Combination therapy can be used for persistent stone formation 6

Acute Pain Management

NSAIDs are superior to opioids and should be first-line therapy:

• Intramuscular diclofenac 75 mg provides pain relief within 30 minutes 7
• NSAIDs reduce ureteral smooth muscle tone and spasm, have fewer side effects, and lower risk of dependence 6, 7
• Reserve opioids (hydromorphine, pentazocine, or tramadol) only when NSAIDs are contraindicated 6, 7
• Avoid pethidine due to high rates of vomiting 7

Medical Expulsive Therapy (MET)

For stones that may pass spontaneously:

• Alpha-blockers (tamsulosin) are recommended, particularly for stones >5 mm in the distal ureter 6, 7
• Conservative management is appropriate for uncomplicated ureteral stones up to 10 mm (AUA) or up to 6 mm (EAU) 6, 7
• Maximum duration of conservative treatment is 4-6 weeks from initial presentation 6, 7

Monitoring and Follow-Up

Structured monitoring is essential to assess treatment response:

• Obtain 24-hour urine collection within 6 months of initiating treatment to verify increased urinary citrate (target >320 mg/day) and adequate urine volume (>2 liters/day) 2, 6
• After initial follow-up, obtain 24-hour urine specimen annually or more frequently depending on stone activity 6
• Measure urinary pH and ensure it does not exceed 7.0 2
• Perform periodic blood testing to assess for adverse effects in patients on pharmacological therapy 6
• Obtain repeat stone analysis when available, especially in patients not responding to treatment 6

Common Pitfalls to Avoid

• Do not restrict dietary calcium - supplemental calcium may increase stone risk, but dietary calcium at normal levels (1,000-1,200 mg/day) is protective 2, 7
• Do not use opioids as first-line pain management - NSAIDs are superior and avoid dependence risks 6, 7
• Do not prescribe allopurinol as first-line therapy for uric acid stones - urinary alkalinization with potassium citrate is correct first-line treatment 6
• Do not recommend "eight glasses of water per day" - tailor recommendations using 24-hour urine volume data with target of at least 2 liters of urine output 2
• Do not use urine color as a guide for adequate hydration - no data supports this approach 2
• Do not delay hospital admission for patients with fever and obstruction - this represents a urologic emergency requiring immediate drainage via percutaneous nephrostomy or ureteral stenting 7
• Do not neglect underlying metabolic abnormalities - stone type determines appropriate medical therapy 6
• Evidence is insufficient to support routine baseline stone composition or urine chemistry testing to predict treatment efficacy, though stone analysis should be performed when stones are passed 1