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

Treatment and Management of Nephrolithiasis

All patients with kidney stones should immediately increase fluid intake to achieve at least 2 liters of urine output daily, and if stones recur despite adequate hydration, initiate pharmacologic monotherapy with thiazide diuretics for hypercalciuria, potassium citrate for hypocitraturia, or allopurinol for hyperuricosuria based on 24-hour urine metabolic profile. 1, 2

Acute Management of Renal Colic

• NSAIDs (diclofenac, ibuprofen, or metamizole) are first-line therapy for acute renal colic pain, as they reduce the need for additional analgesia compared to opioids 3
• Use opioids (hydromorphine, pentazocine, or tramadol—avoid pethidine) only when NSAIDs are contraindicated or insufficient 3
• Alpha-blockers are strongly recommended for ureteral stones >5 mm in the distal ureter to facilitate spontaneous passage in patients suitable for conservative management 3
• Urgent decompression via percutaneous nephrostomy or ureteral stenting is mandatory for sepsis and/or anuria in an obstructed kidney, with immediate antibiotic administration 3

Initial Non-Pharmacologic Management (Foundation for All Stone Types)

Fluid Intake (Most Critical Intervention)

• Increase water intake to produce at least 2 liters of urine output per 24 hours, which reduces stone recurrence by approximately 55% (relative risk 0.45,95% CI 0.24-0.84) 2, 4
• For severe stone formers (primary hyperoxaluria, enteric hyperoxaluria, or cystinuria), increase fluid intake to achieve 3.5-4 liters of urine output daily 5
• Balance fluid intake between day and night to avoid urinary supersaturation during nighttime hours 5
• Water is the beverage of choice; coffee, tea, wine, and orange juice may be protective 6

Dietary Modifications

• Maintain normal dietary calcium intake of 1,000-1,200 mg per day—never restrict calcium, as calcium restriction paradoxically increases urinary oxalate and stone risk 2, 6
• Limit sodium intake to 2,300 mg daily to reduce urinary calcium excretion 2, 6
• Reduce non-dairy animal protein to 5-7 servings of meat, fish, or poultry per week, as animal protein generates sulfuric acid, increasing urinary calcium and reducing citrate 2, 6
• Limit high-oxalate foods (nuts, chocolate, tea, spinach, wheat bran) particularly in patients with hyperoxaluria 2, 6
• Avoid sugar-sweetened beverages, especially colas acidified with phosphoric acid (relative risk 0.83 for recurrence) 2, 6
• Avoid vitamin C supplements >1,000 mg/day, as vitamin C metabolizes to oxalate and increases stone risk 2, 6

Pharmacologic Management (When Hydration Alone Fails)

The American College of Physicians recommends pharmacologic monotherapy when increased fluid intake alone fails to prevent stone formation, choosing one agent based on metabolic abnormalities identified on 24-hour urine collection. 1, 2

Calcium Oxalate Stones

Thiazide Diuretics (First-Line for Hypercalciuria)

• Indicated for patients with high or relatively high urinary calcium, reducing composite stone recurrence from 48.5% to 24.9% 1, 2
• No significant differences exist between different types of thiazides or varying dosages 1
• Monitor for hypokalemia and glucose intolerance with periodic blood testing 1

Potassium Citrate (First-Line for Hypocitraturia)

• Indicated for patients with low or relatively low urinary citrate (target >320 mg/day), reducing composite stone recurrence from 52.3% to 11.1% 1, 2
• For severe hypocitraturia (urinary citrate <150 mg/day): initiate 60 mEq/day (30 mEq twice daily or 20 mEq three times daily with meals) 7
• For mild to moderate hypocitraturia (urinary citrate >150 mg/day): initiate 30 mEq/day (15 mEq twice daily or 10 mEq three times daily with meals) 7
• Doses >100 mEq/day have not been studied and should be avoided 7
• Monitor for hyperkalemia with periodic blood testing 1, 7

Allopurinol (First-Line for Hyperuricosuria)

• Indicated for patients with recurrent calcium oxalate stones who have hyperuricosuria (>800 mg/day) and normal urinary calcium, reducing composite stone recurrence from 55.4% to 33.3% 1, 2
• Hyperuricemia is not a required criterion for allopurinol therapy 1
• Monitor for elevated liver enzymes with periodic blood testing 1

Uric Acid Stones

• Potassium citrate is first-line therapy to raise urine pH to 6.0, as most patients have low urinary pH rather than hyperuricosuria as the predominant risk factor 1, 3, 7
• Do not routinely offer allopurinol as first-line therapy for uric acid stones, as reduction of urinary uric acid excretion will not prevent stones in patients with unduly acidic urine 1
• Oral chemolysis with alkalinization (citrate or sodium bicarbonate to pH 7.0-7.2) can dissolve existing uric acid stones 3

Cystine Stones

• First-line therapy includes increased fluid intake, sodium and protein restriction, and urinary alkalinization with potassium citrate to achieve urine pH of 7.0 1, 3, 7
• Offer cystine-binding thiol drugs (tiopronin preferred over d-penicillamine) to patients unresponsive to dietary modifications and urinary alkalinization, or with large recurrent stone burdens 1
• Monitor for elevated liver enzymes and anemia with periodic blood testing 1

Monitoring and Follow-Up

• Obtain 24-hour urine collection within 6 months of treatment initiation to assess response to dietary/medical therapy, measuring volume, pH, calcium, oxalate, uric acid, citrate, sodium, potassium, and creatinine 1, 3, 7
• Continue annual 24-hour urine collections to assess adherence and metabolic response, with greater frequency depending on stone activity 1
• Obtain periodic blood testing to assess for adverse effects in patients on pharmacologic therapy 1, 3
• Perform stone analysis for all first-time stone formers, and obtain repeat analysis in patients not responding to treatment 3

Critical Pitfalls to Avoid

• Never restrict dietary calcium—this increases urinary oxalate and stone risk 2, 6
• Do not use sodium-based alkali (sodium citrate/bicarbonate) instead of potassium citrate, as the sodium load increases urinary calcium 6
• Do not use combination therapy as first-line—monotherapy is equally effective with fewer side effects 2
• Avoid calcium supplements unless specifically indicated; prefer dietary calcium sources consumed with meals to bind oxalate 2, 6
• Do not use allopurinol as first-line therapy for uric acid stones when the primary problem is low urinary pH 1
• Do not ignore vitamin C supplements—they metabolize to oxalate and increase stone risk at doses >1,000 mg/day 2, 6