What is the treatment for nephrolithiasis (kidney stones)?

Treatment of Nephrolithiasis

Acute Pain Management

NSAIDs (diclofenac, ibuprofen, or metamizole) are the first-line therapy for acute renal colic, as they reduce the need for additional analgesia compared to opioids. 1

• Use NSAIDs at the lowest effective dose due to cardiovascular and gastrointestinal risks 1
• Opioids (hydromorphine, pentazocine, or tramadol—but not pethidine) serve as second-line agents when NSAIDs are contraindicated or insufficient 1

Emergency Interventions

Urgent decompression via percutaneous nephrostomy or ureteral stenting is mandatory for sepsis and/or anuria in an obstructed kidney. 1

• Administer antibiotics immediately and adjust based on culture results in infected obstructed systems 1
• Alpha-blockers are strongly recommended for ureteral stones >5 mm in the distal ureter in patients suitable for conservative management 1

Non-Pharmacological Management (First-Line for All Stone Types)

Increase fluid intake to achieve at least 2 liters of urine output daily—this is the cornerstone of both primary and secondary prevention. 2, 3, 1

Fluid Intake Recommendations:

• Target urine output of at least 2 liters per day, with some severe forms requiring 3.5-4 L/day (primary or enteric hyperoxaluria, cystinuria) 4
• Increasing fluid intake reduces stone recurrence risk by approximately 55% (RR 0.45,95% CI 0.24-0.84) 2
• Balance fluid intake between day and night to avoid urinary supersaturation during nighttime 4
• Water is the liquid of choice; no significant difference exists between tap water and mineral water 3
• Beverages like coffee, tea, wine, and orange juice may be associated with lower stone risk 2
• Avoid sugar-sweetened beverages, particularly colas acidified with phosphoric acid (RR 0.83 for recurrence when avoided) 2, 3

Dietary Modifications for Calcium Stones:

• Maintain normal dietary calcium intake of 1,000-1,200 mg/day—do NOT restrict calcium 2, 1
• Restricting dietary calcium paradoxically increases stone risk by increasing urinary oxalate 2
• Limit sodium intake to 2,300 mg daily to reduce urinary calcium excretion 2
• Reduce non-dairy animal protein intake to 5-7 servings of meat, fish, or poultry per week 2
• Limit high-oxalate foods (certain nuts, vegetables, wheat bran, chocolate, tea, strawberries) particularly for patients with hyperoxaluria 2
• Consume calcium from foods primarily at meals to enhance gastrointestinal binding of oxalate 2
• Avoid calcium supplements unless specifically indicated, as they increase stone risk compared to dietary calcium 2
• Limit vitamin C supplements, as vitamin C is metabolized to oxalate 2

Pharmacological Management (When Fluid Intake Fails)

When increased fluid intake fails to prevent stone formation, initiate pharmacologic therapy based on 24-hour urine metabolic abnormalities. 3

For Calcium Stones with Hypercalciuria:

• Thiazide diuretics are first-line therapy (hydrochlorothiazide 50 mg or chlorthalidone 25-50 mg) 2, 1
• Reduces recurrence with RR 0.52 (95% CI 0.39-0.69) 2

For Calcium Stones with Hypocitraturia:

• Potassium citrate is first-line therapy (typically 20 mEq three times daily, range 30-100 mEq/day) 2, 5
• Highly effective with RR 0.25 for recurrence (95% CI 0.14-0.44) 2
• Raises urinary citrate from subnormal to normal values (400-700 mg/day) and increases urinary pH to approximately 6.5 5
• Stone formation rate reduced by 80% overall in clinical trials 5
• Do NOT use sodium citrate instead of potassium citrate, as the sodium load increases urinary calcium 2

For Calcium Oxalate Stones with Hyperuricosuria:

• Allopurinol 200-300 mg/day for patients with hyperuricemia or hyperuricosuria and normal urinary calcium 2, 3
• Reduces recurrence with RR 0.59 (95% CI 0.42-0.84) 2

For Uric Acid Stones:

• Potassium citrate is first-line therapy to raise urine pH to 6.0 1
• Most patients have low urinary pH rather than hyperuricosuria as the predominant risk factor 1
• Oral chemolysis with alkalinization (citrate or sodium bicarbonate to pH 7.0-7.2) can dissolve existing uric acid stones 1

For Cystine Stones:

• Stepwise approach: increased fluid intake, sodium and protein restriction, and urinary alkalinization with potassium citrate to achieve urine pH of 7.0 1

Monotherapy vs. Combination:

• Monotherapy is generally as effective as combination therapy and should be preferred to minimize adverse effects 3, 1

Monitoring and Follow-up

Obtain 24-hour urine collections to assess metabolic abnormalities and guide therapy. 2, 1

• Measure volume, pH, calcium, oxalate, uric acid, citrate, sodium, potassium, and creatinine 2, 1
• Obtain 24-hour urine collection within 6 months of treatment initiation to assess response 1
• Continue annual 24-hour urine collections to assess adherence and metabolic response 1
• Perform stone analysis for all first-time stone formers 1
• Obtain repeat stone analysis in patients not responding to treatment, as stone composition may change 1
• Monitor for adverse effects: hypokalemia and glucose intolerance (thiazides), elevated liver enzymes (allopurinol), hyperkalemia (potassium citrate) 1

Common Pitfalls to Avoid

• Never restrict dietary calcium—this paradoxically increases stone risk by increasing urinary oxalate 2
• Do not use sodium citrate instead of potassium citrate 2
• Do not overrely on calcium supplements rather than dietary calcium sources 2
• Do not recommend oxalate restriction to individuals with pure uric acid stones or those with low urinary oxalate excretion 2