In an otherwise healthy adult with a non‑obstructive renal calculus, does it cause chronic kidney disease and require removal?

Non-Obstructive Renal Calculi and Chronic Kidney Disease Risk

Non-obstructive renal calculi are independently associated with increased risk of chronic kidney disease (CKD) and should be considered for removal when they demonstrate growth, cause symptoms, or occur in high-risk stone formers, though asymptomatic small stones can be safely observed with regular imaging surveillance. 1, 2

Evidence for CKD Risk in Non-Obstructive Stone Disease

The relationship between kidney stones and CKD exists even without obstruction:

• The European Association of Urology explicitly states that urolithiasis, even when non-obstructive, is independently associated with increased risk of CKD and progression to end-stage renal disease (ESRD). 2 This represents the most current guideline position on this question.

• All stone formers should be considered at risk for CKD regardless of obstruction presence, warranting systematic renal function evaluation. 2

• Population-based studies confirm stone formers have increased risk for sustained elevated serum creatinine, sustained reduced GFR (<60 ml/min per 1.73 m²), and clinical CKD diagnosis compared to matched controls, even after adjusting for hypertension, diabetes, and other comorbidities. 3

• The mechanisms of renal injury extend beyond simple obstruction and include crystal plugs at the ducts of Bellini, parenchymal injury, recurrent subclinical inflammation, and direct tissue damage from crystal formation itself. 4, 5

Indications for Removal of Non-Obstructive Stones

The 2025 European Association of Urology guidelines provide clear criteria for when non-obstructive renal stones require removal: 1

• Stone growth on serial imaging 1
• High risk of stone formation (recurrent stone formers, metabolic abnormalities) 1
• Development of symptoms (even if non-obstructive) 1
• Recurrent extensive nephrolithiasis 1

Management Algorithm for Asymptomatic Non-Obstructive Stones

Small Stones (<10mm)

• Observation with periodic imaging is the appropriate initial management approach. 6
• Follow-up imaging at 3-6 months intervals to assess for stone passage or growth. 6
• Natural history data shows that 28% of asymptomatic non-obstructing stones cause symptoms during average 41-month follow-up, with only 7% passing spontaneously. 7
• Critical caveat: 2-3% of asymptomatic stones can cause painless silent obstruction, necessitating regular imaging surveillance to prevent renal loss. 7

Moderate Stones (5-10mm)

• Observation remains acceptable for controlled symptoms. 6
• When intervention is needed, both shock wave lithotripsy (SWL) and ureteroscopy (URS) are first-line options, though URS yields significantly higher stone-free rates with higher complication rates. 6

Large Stones (>10mm)

• Surgical treatment is required in most cases. 6
• For stones >20mm, percutaneous nephrolithotomy (PCNL) is the first-line treatment regardless of location. 6

High-Risk Populations Requiring More Aggressive Management

Certain stone formers are at substantially elevated CKD risk and warrant lower thresholds for intervention: 4

• Hereditary stone diseases (cystinuria, primary hyperoxaluria, Dent disease, 2,8-dihydroxyadenine stones)
• Recurrent urinary tract infections or struvite stones
• Comorbid hypertension or diabetes
• Larger stone burden (positive association between stone size and renal dysfunction) 5

Medical Prevention Strategies

For all stone formers, regardless of whether stones are removed: 1

• Increase fluid intake to achieve at least 2 liters (preferably ≥2.5 liters) of urine output daily—this is the single most critical preventive measure. 1, 6
• For active recurrent disease where increased fluid fails, add pharmacologic monotherapy with thiazide diuretic, citrate, or allopurinol. 1

Critical Pitfalls to Avoid

• Do not assume non-obstructive stones are benign—they independently increase CKD risk and require monitoring. 2
• Do not rely solely on symptom development—silent obstruction can occur in 2-3% of cases, mandating regular imaging. 7
• Do not use ultrasound alone for small stones; CT provides definitive diagnosis when clinical suspicion is high. 6
• Do not neglect renal function monitoring—obtain baseline and serial creatinine/eGFR measurements in all stone formers. 1, 2
• Lower pole stones are significantly less likely to pass spontaneously (2.9% vs 14.5% for upper/mid pole), influencing observation versus intervention decisions. 7