In an otherwise healthy adult with a confirmed renal stone and no infection, obstruction, or impaired renal function, what is the first‑line outpatient management?

Outpatient Management of Nephrolithiasis

For an otherwise healthy adult with a confirmed renal stone and no infection, obstruction, or impaired renal function, first-line outpatient management consists of increased fluid intake to achieve at least 2 liters of urine output daily, combined with pain control using NSAIDs and observation for spontaneous passage if the stone is ≤10 mm. 1

Initial Assessment and Risk Stratification

Determine Stone Size and Location

• Stones <5 mm: Expect spontaneous passage in most cases without intervention 2, 3
• Stones 5-10 mm: Up to 50% may require intervention, but initial conservative management is appropriate 3
• Stones >10 mm: Unlikely to pass spontaneously and should be discussed with urology 3, 4

Confirm Absence of Urgent Indications

Before proceeding with outpatient management, verify:

• No signs of infection or sepsis (fever, purulent urine) - these require urgent drainage 5, 6
• No complete obstruction with impaired renal function - requires urgent intervention 6
• Pain is controllable with oral medications 4

First-Line Conservative Management

Fluid Intake (Cornerstone of Therapy)

• Increase fluid intake throughout the day to achieve at least 2 liters of urine output daily (weak recommendation, low-quality evidence) 1
• This reduces urinary concentration of stone-forming substances and facilitates stone passage 1

Pain Management

• NSAIDs are first-line analgesics: Diclofenac 50-100 mg rectally or 75 mg IM is reasonable first choice 3
• Combination of diclofenac, paracetamol, and/or codeine can provide adequate control 3
• Opioids are less effective and worsen nausea, but use if NSAIDs contraindicated 3

Medical Expulsive Therapy

• Alpha-blockers may facilitate stone passage, particularly for ureteral stones 5
• Consider for stones 5-10 mm to increase spontaneous passage rates 4

Follow-up Imaging

• Obtain follow-up imaging within 14 days to monitor stone position and assess for hydronephrosis 4
• Plain film KUB can be used for radiopaque stones 3

When Conservative Management Fails

Indications for Urologic Referral

• Failed medical expulsive therapy after 4-6 weeks 6
• Uncontrolled pain despite combination analgesics 3, 4
• Stone >10 mm at initial diagnosis 3, 4
• Patient preference for earlier definitive intervention 6

Common Pitfall to Avoid

Do not delay urologic referral beyond 4-6 weeks of failed conservative management, as complete obstruction beyond this timeframe risks irreversible kidney injury 6

Prevention of Recurrence

For All Patients After First Stone

• Maintain increased fluid intake to achieve at least 2 L urine output daily (weak recommendation, low-quality evidence) 1
• Limit sodium intake to approximately 2,300 mg per day 5
• Ensure dietary calcium consumption of 1,000-1,200 mg per day (do not restrict calcium) 5
• Reduce soft-drink consumption (low-strength evidence for benefit) 1

For Patients with Recurrent Stones

If increased fluid intake fails to prevent recurrence:

• Add pharmacologic monotherapy with thiazide diuretic, citrate, or allopurinol (weak recommendation, moderate-quality evidence) 1
• Thiazides reduce recurrence risk (RR 0.52,95% CI 0.39-0.69) 1
• Citrates reduce recurrence risk (RR 0.25,95% CI 0.14-0.44) 1
• Allopurinol reduces recurrence risk (RR 0.59,95% CI 0.42-0.84), though benefit appears limited to patients with hyperuricemia or hyperuricosuria 1

Metabolic Evaluation

• Perform 24-hour urine metabolic testing in high-risk patients or those with recurrent stones to identify modifiable risk factors 5
• Stone analysis is mandatory to guide prevention strategies 5

Natural History and Prognosis

• Spontaneous passage occurs in approximately 29% of asymptomatic stones during follow-up 7
• 50% of patients develop symptoms by 19 months after diagnosis 7
• 5-year recurrence rate is 35-50% without specific preventive treatment 1, 8
• Male gender, younger age, and history of prior stones increase risk of stone-related events 7