What is the best course of treatment for an adult patient with no significant medical history presenting with a renal stone?

Treatment of Renal Stones in Adults

For an adult with no significant medical history presenting with a renal stone, the treatment approach depends primarily on stone size: stones ≤20 mm should be managed with either shock wave lithotripsy (SWL) or ureteroscopy (URS), while stones >20 mm require percutaneous nephrolithotomy (PCNL) as first-line therapy. 1, 2

Initial Evaluation

Before determining treatment, perform a screening evaluation that includes 1:

• Detailed medical and dietary history to identify predisposing conditions and dietary habits 1
• Serum chemistries (electrolytes, calcium, creatinine, uric acid) to detect underlying metabolic conditions 1
• Urinalysis with both dipstick and microscopic examination to assess urine pH, identify infection indicators, and detect pathognomonic crystals 1
• Imaging studies to quantify stone burden and location 1
• Stone analysis (when available) to guide preventive measures 1

Treatment Algorithm Based on Stone Size

Stones ≤20 mm (Non-Lower Pole)

Both SWL and URS are acceptable first-line options 1, 2:

• URS achieves stone-free status more quickly with lower likelihood of requiring repeat procedures compared to SWL 1, 2
• Stone-free rates for both modalities are acceptable for this size range, though both decline with increasing stone burden 1
• Patient-specific factors influence choice: body habitus, stone composition, stone density, and collecting system anatomy affect SWL success 1

Stones >20 mm

PCNL must be offered as first-line therapy 1, 2:

• PCNL achieves superior stone-free rates (94% vs 75% for URS in randomized trials) 1, 2
• PCNL success is less dependent on stone composition, density, and location compared to other modalities 1
• SWL should NOT be offered as first-line therapy for stones >20 mm due to significantly reduced stone-free rates and increased need for multiple treatments 1, 2

Lower Pole Stones (Special Considerations)

The European Association of Urology 2025 guidelines provide specific guidance 1:

• Stones ≤10 mm: SWL or URS are both appropriate options 2
• Stones >10 mm: SWL should not be offered as first-line therapy; URS or PCNL are preferred 2
• Stones 10-20 mm: PCNL is recommended over other modalities 2

Urgent Intervention Indications

Emergency decompression is mandatory in specific scenarios 1, 2:

• Obstructing stones with suspected infection or sepsis require urgent drainage via nephrostomy tube or ureteral stent before definitive stone treatment 1, 2
• The collecting system must be drained to allow infected urine drainage and antibiotic penetration 1
• Stone treatment should be delayed until infection is controlled 1

Conservative Management

For asymptomatic or minimally symptomatic stones, observation may be appropriate 3:

• Stones <5 mm typically pass spontaneously and can be managed conservatively 3
• Maximum observation period should not exceed 4-6 weeks to avoid irreversible kidney injury 1, 2
• Alpha-blockers may facilitate stone passage during observation 1

Prevention of Recurrence

After acute management, implement preventive strategies 1:

Dietary Modifications

Increase fluid intake to achieve at least 2 liters of urine output daily 1:

• This is the cornerstone of stone prevention regardless of stone type 1
• Fluid intake should be spread throughout the day 1

Pharmacologic Therapy

When increased fluid intake fails to prevent recurrence, initiate monotherapy with 1:

• Thiazide diuretics (hydrochlorothiazide 50 mg, chlorthalidone 25-50 mg, or indapamide 2.5 mg) 1
• Citrate supplementation 1
• Allopurinol 1

All three agents effectively reduce recurrence of calcium stones, which comprise the majority of renal stones 1. Combination therapy offers no additional benefit over monotherapy 1.

Critical Pitfalls to Avoid

• Never delay intervention beyond 4-6 weeks for stones requiring treatment, as this risks irreversible kidney injury 1, 2
• Always obtain urinalysis and urine culture before intervention to identify unrecognized infection 1
• Do not restrict dietary calcium in stone formers, as this may paradoxically increase stone risk 4
• Avoid using SWL as first-line therapy for stones >20 mm due to poor outcomes 1, 2
• Do not perform stone intervention in the setting of active infection without first draining the collecting system 1