What are the management options for renal calculi?

Management of Renal Calculi

For renal stones <10mm, observation with periodic imaging is the initial management approach, while stones >10mm typically require surgical intervention with either shock wave lithotripsy (SWL) or ureteroscopy (URS) as first-line options. 1

Initial Assessment and Risk Stratification

Diagnostic Workup

• Obtain non-contrast CT scan as the gold standard imaging modality for stone detection and characterization, though low-dose CT protocols should be used to minimize radiation exposure 2
• Ultrasound is acceptable as first-line imaging but may miss stones <3mm 3
• Perform stone analysis at least once when stone material is available to guide preventive strategies 1
• Obtain serum calcium and intact parathyroid hormone if primary hyperparathyroidism is suspected (high or high-normal calcium) 1
• Quantify stone burden through imaging to assess for multiple/bilateral stones or nephrocalcinosis, which indicate higher recurrence risk 1

Metabolic Evaluation

• Perform 24-hour urine collection (preferably two collections) in high-risk or recurrent stone formers, analyzing for volume, pH, calcium, oxalate, uric acid, citrate, sodium, potassium, and creatinine 1
• Obtain urinalysis and urine culture if infection is suspected or patient has recurrent UTIs 1

Management Based on Stone Size and Location

Small Renal Stones (≤5mm)

• Conservative management with observation is appropriate for asymptomatic or mildly symptomatic stones, as spontaneous passage rates are high 3, 2
• Medical expulsive therapy with tamsulosin 0.4mg daily, combined with furosemide 20mg, spironolactone 50mg, and potassium magnesium citrate 20mEq three times daily for 12 weeks achieves 86% stone clearance versus 38% with placebo 4
• Follow-up imaging at 3-6 months to assess for stone passage or growth 3
• Intervene if stone grows, causes obstruction/infection, or patient preference after counseling 3

Moderate Renal Stones (5-10mm)

• Observation with periodic imaging remains an option for controlled symptoms 1
• Patients must have well-controlled pain, no sepsis, and adequate renal function 1
• Both SWL and URS are acceptable first-line treatments when intervention is needed 1
• URS yields significantly higher stone-free rates but has higher complication rates (ureteral injury 3-6%, stricture 1-2%) compared to SWL 1

Large Renal Stones (>10mm)

• Surgical treatment is required in most cases 1
• For lower pole stones 1-2cm, percutaneous nephrolithotomy (PNL) is preferred, though URS is acceptable in select patients 5
• For stones >2cm, PNL is the definitive treatment with superior stone-free rates 5

Staghorn Calculi

• PNL is the treatment of choice based on superior outcomes and acceptable morbidity 6
• If affected kidney has negligible function and contralateral kidney is normal, consider nephrectomy, especially with xanthogranulomatous pyelonephritis 6, 7
• Obtain urine culture before antibiotics and treat with broad-spectrum parenteral therapy (fluoroquinolone, aminoglycoside, or extended-spectrum cephalosporin) for 7-14 days 7

Surgical Technique Considerations

SWL vs URS Decision-Making

• Counsel patients that URS provides better stone-free rates with single procedure but carries higher complication risks 1
• SWL complications: sepsis 3-5%, steinstrasse 4-8%, stricture 0-2%, UTI 4-6% 1
• URS complications: sepsis 2-4%, ureteral injury 3-6%, stricture 1-4%, UTI 2-4% 1
• Routine stenting is not recommended with SWL as it provides no improved fragmentation 1

Special Populations

• Pediatric patients can be managed with both SWL and URS, with similar complication profiles to adults 1
• For lower pole stones <1cm, observation, SWL, or URS are all viable, with SWL preferred due to favorable secondary outcomes 5

Medical Prevention Strategies

Universal Recommendations

• Increase fluid intake to achieve urine volume ≥2.5 liters daily as the most critical preventive measure 1
• Moderate intake of salt, calcium (not restriction), and animal protein 8

Targeted Pharmacotherapy Based on Stone Type

• Thiazide diuretics (calcium-sparing) for hypercalciuria 8
• Potassium citrate to increase urinary citrate, a natural stone inhibitor 8
• Allopurinol for hyperuricosuria 8
• Oral chemolysis is an option for uric acid stones 2
• Urease inhibitors (acetohydroxamic acid) for recurrent infection stones after removal 7

Critical Pitfalls to Avoid

• Do not rely solely on ultrasound for small stones - use CT for definitive diagnosis when clinical suspicion is high 3
• Do not assume absence of hydronephrosis rules out obstruction - dehydration can mask hydronephrosis 3
• Do not routinely stent with SWL - no benefit and increases morbidity 1
• Do not restrict calcium intake - this paradoxically increases stone risk 8
• For patients electing observation or medical expulsive therapy, ensure well-controlled pain, no sepsis, and adequate renal function before proceeding 1