Kidney Stone Management

Introduction to Kidney Stone Prevention

• The American Urological Association recommends increased fluid intake (at least 2.5 liters per day) as the cornerstone of kidney stone prevention, which decreases urinary concentration and prevents stone formation (strength of evidence level I) 1
• The American College of Physicians notes that treatment should be tailored to the specific type of stone (calcium oxalate, calcium phosphate, uric acid, cystine, or struvite) 1, 2

Diagnostic Considerations

• Imaging studies, such as non-contrast CT scan or ultrasound, are necessary for diagnosis and treatment planning 3
• Consider repeat imaging with non-contrast CT scan if symptoms persist beyond 6 weeks of medical therapy 4
• Consider cystoscopy if symptoms persist despite medical management 5
• Uric acid stones are typically radiolucent and may be difficult to visualize on imaging, particularly when small 6

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Pharmacological Management

• The European Association of Urology recommends thiazide diuretics for hypercalciuria in patients with calcium stones, potassium citrate to raise urinary pH to 6.0 for uric acid stones, potassium citrate therapy for low urinary citrate, and allopurinol for hyperuricosuria with normal calcium 2
• Target urinary pH of 6.0-7.0 with potassium citrate therapy (30-80 mEq per day divided in 3-4 doses) for uric acid stones 6, 7
• Maintain a low pH for patients with calcium phosphate or struvite stones 2, 7
• Thiazide diuretics (e.g., hydrochlorothiazide or chlorthalidone) for patients with high urinary calcium (Grade B evidence) 2
• Potassium citrate for patients with low urinary citrate or low urinary pH 2
• Allopurinol for patients with hyperuricosuria and normal urinary calcium (Grade B evidence) 2
• Aluminum hydroxide (50-100 mg/kg/day divided in 4 doses) for phosphate crystal management 8

Dietary Considerations

• Increase fluid intake to at least 2.5 liters per day to decrease urinary concentration and prevent stone formation (strength of evidence level I) 2, 1
• For patients with primary hyperoxaluria, more aggressive hydration is required: 3.5-4 liters/day for adults and 2-3 liters/m² body surface area for children (strength of evidence level III) 9
• Limit sodium intake to approximately 2,300 mg (100 mEq) daily to reduce urinary calcium excretion (strength of evidence level II) 2, 1
• Limit protein intake to 5-7 servings of meat, fish, or poultry per week (strength of evidence level II) 2, 1
• Maintain normal dietary calcium intake of 1,000-1,200 mg per day from food sources, consumed with meals to reduce oxalate absorption (strength of evidence level I) 2, 1
• Limit intake of oxalate-rich foods for patients with calcium oxalate stones (strength of evidence level II) 2, 1, 10

Surgical Considerations

• Consider surgical treatment if stone growth occurs, patient develops symptoms, associated infection develops, or specific vocational reasons necessitate removal 11
• Treatment of bladder stones is essential for resolution of symptoms including dyspareunia 12

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Follow-up and Monitoring

• Measure 24-hour urinary parameters within 6 months of initiating treatment, then annually or more frequently based on stone activity (monitoring volume, pH, calcium, oxalate, uric acid, citrate, sodium, potassium, and creatinine) 2
• Obtain periodic blood testing to assess for adverse effects in patients on pharmacological therapy (electrolytes, glucose, liver enzymes, CBC) 2
• Periodic follow-up imaging to assess for stone growth or new stone formation (strength of evidence level II) 3, 6, 11, 13, 5
• Evaluate for underlying metabolic disorders (renal tubular acidosis, hyperparathyroidism, X-linked hypophosphatemia) in patients with phosphate crystalluria 14, 15, 16

Clinical Considerations

• Bladder stones can cause pain during intercourse due to direct mechanical irritation 12
• Bladder stones are a clinical mimic of interstitial cystitis/bladder pain syndrome, which commonly presents with dyspareunia 12