How do I manage a patient with a kidney stone?

Management of Kidney Stones

Initial Assessment and Diagnosis

Obtain a detailed medical and dietary history, serum chemistries (electrolytes, calcium, creatinine, uric acid), and urinalysis with microscopy to identify stone type and underlying metabolic disorders. 1

• Assess pain characteristics including location, intensity, radiation pattern, and timing to guide immediate management decisions 2
• Order urine culture if urinalysis suggests infection or if the patient has recurrent UTIs 1
• Obtain imaging studies to quantify stone burden and guide treatment—ultrasound is first-line, particularly in pregnancy, while non-contrast CT provides definitive diagnosis 2
• Strain urine to capture stone material for analysis, which should be obtained at least once to guide prevention strategies 2, 1

Acute Pain Management

Administer NSAIDs as first-line treatment for renal colic, with opioids reserved for breakthrough pain. 2

• Provide intravenous fluids if the patient cannot tolerate oral intake 2
• Most stones (approximately 90%) will pass spontaneously within 3 days, particularly those <5mm 3, 4
• Alpha-blockers (such as tamsulosin) can facilitate spontaneous stone passage 5

Emergency Indications Requiring Urgent Intervention

If purulent urine is encountered or infection is suspected with obstruction, immediately abort any stone removal procedure, establish drainage with ureteral stent or nephrostomy tube, obtain urine culture, and continue broad-spectrum antibiotics. 6

• This represents a urologic emergency requiring immediate drainage to prevent sepsis and renal damage 6, 3
• Delay definitive stone treatment until infection is controlled 7
• Other indications for urgent intervention include high-grade obstruction, failure of oral analgesics, or signs of acute kidney injury 2, 3

Surgical Management Based on Stone Size and Location

For Stones ≤10mm

Offer either shock wave lithotripsy (SWL) or ureteroscopy (URS) as first-line treatment, with SWL providing better quality of life outcomes but URS achieving higher stone-free rates (90% vs 72%). 7

• Patient-derived quality of life measures favor SWL in this size range 7
• Intraoperative complications may be slightly higher with URS, though not statistically significant 7

For Stones 10-20mm

Offer URS or percutaneous nephrolithotomy (PCNL) rather than SWL, as success rates drop significantly for SWL in this range. 7

• Median success rates: URS 81%, PCNL 87%, SWL only 58% for lower pole stones 7
• For lower pole stones >10mm, SWL should NOT be offered as first-line therapy due to poor outcomes 7

For Stones >20mm

Offer PCNL as first-line therapy due to significantly higher stone-free rates (87-94%) compared to other modalities. 7

• Open, laparoscopic, or robotic surgery should not be offered as first-line except in rare cases of anatomic abnormalities requiring concomitant reconstruction 6

Procedural Considerations

Use a safety guidewire for most endoscopic procedures to facilitate rapid re-access if the primary wire is lost or displaced. 6

• Administer antimicrobial prophylaxis within 60 minutes of ureteroscopic or PCNL procedures based on prior urine culture results and local antibiogram 6
• SWL does not require antimicrobial prophylaxis in the absence of UTI 6
• Use normal saline irrigation during PCNL to prevent electrolyte abnormalities 7
• Routine stent placement after uncomplicated URS is not recommended 7
• Flexible nephroscopy should be performed during PCNL to access stone fragments in areas inaccessible by rigid nephroscope 7

Management of Residual Fragments

Offer endoscopic procedures to render patients stone-free when residual fragments are present, especially if infection stones are suspected. 6

• 43% of patients with residual fragments after PCNL experience stone-related events at median 32 months 6
• 29% of patients with residual fragments after URS require intervention 6
• Removal of suspected infection stones limits recurrent UTI, further stone growth, and renal damage 6

Long-Term Prevention Strategies

Fluid and Dietary Modifications

Advise patients to increase fluid intake to achieve urine volume of at least 2.5 liters daily. 2, 1

• Maintain normal dietary calcium intake (1,000-1,200 mg/day) from food sources, not supplements 2
• Limit sodium intake to 2,300 mg daily 2
• Avoid calcium supplements, which increase stone risk unlike dietary calcium 2
• Encourage coffee, tea, wine, and orange juice; avoid sugar-sweetened beverages 2
• For calcium oxalate stones, limit oxalate-rich foods while maintaining normal calcium consumption 2

Medical Management for Recurrent Stones

Offer thiazide diuretics to patients with high or relatively high urine calcium and recurrent calcium stones. 6

• Effective dosages: hydrochlorothiazide 25mg twice daily or 50mg once daily, chlorthalidone 25mg once daily, or indapamide 2.5mg once daily 6
• Continue dietary sodium restriction to maximize hypocalciuric effect and limit potassium wasting 6
• Potassium supplementation (citrate or chloride) may be needed 6

Offer potassium citrate therapy to patients with recurrent calcium stones and low or relatively low urinary citrate. 6

• Potassium citrate is preferred over sodium citrate, as sodium load increases urine calcium excretion 6
• Particularly important for calcium phosphate stone formers with hypocitraturia 6

Offer allopurinol to patients with recurrent calcium oxalate stones who have hyperuricosuria (>800 mg/day) and normal urinary calcium. 6

• Hyperuricemia is not required for allopurinol therapy 6

Offer potassium citrate to patients with uric acid and cystine stones to raise urinary pH to optimal levels. 6

• Solubility of uric acid and cystine increases at higher urinary pH values 6

Metabolic Evaluation for High-Risk Patients

Consider 24-hour urine collection for metabolic evaluation in recurrent stone formers or high-risk first-time formers (solitary kidney, large stone burden, refractory to other measures). 6, 2, 1

• Stone analysis should be obtained at least once when material is available 2, 1
• High-risk patients include those with family history, hyperparathyroidism, renal tubular acidosis, or inflammatory bowel disease 2

Common Pitfalls to Avoid

• Do not restrict dietary calcium, as this may worsen oxaluria and increase stone risk 2, 3
• Do not offer SWL for stones >10mm in lower pole location due to poor success rates (58% for 10-20mm, only 10% for >20mm) 7
• Do not proceed with stone removal if purulent urine is encountered—this mandates drainage and antibiotic therapy first 6
• Do not assume normal kidney function in stone formers, as even common calcium oxalate stone patients have decreased creatinine clearance compared to normal individuals 8