What are the treatment options for a patient with kidney stones?

Treatment of Kidney Stones

For acute renal colic, administer NSAIDs (diclofenac 75 mg IM, ibuprofen, or metamizole) as first-line therapy—not opioids—as they provide superior pain control within 30 minutes while directly addressing ureteral spasm and avoiding dependence risks. 1, 2, 3

Immediate Assessment and Triage

Emergency intervention is mandatory for patients presenting with: 1, 2, 3

• Sepsis with obstructed kidney (fever + stone)
• Anuria with obstruction
• Shock or hemodynamic instability
• Pain unresponsive to analgesia within one hour
• Abrupt recurrence of severe pain after initial relief

In these cases, perform urgent decompression via percutaneous nephrostomy or ureteral stenting immediately, collect urine for culture before and after decompression, administer broad-spectrum antibiotics, and delay definitive stone treatment until sepsis resolves. 1, 2

Initial Diagnostic Workup

Perform the following evaluation for all newly diagnosed patients: 1, 3

Laboratory testing:

• Serum chemistries: electrolytes, calcium, creatinine, uric acid 1
• Urinalysis with dipstick and microscopy to assess pH, infection, and identify pathognomonic crystals 1
• Urine culture if infection suspected 1
• Serum intact parathyroid hormone if primary hyperparathyroidism suspected (high or high-normal calcium) 1

Imaging:

• Renal ultrasonography as first-line modality 3, 4
• Non-contrast CT after ultrasound for acute flank pain to assess stone location, burden, density, and anatomy 1
• Low-dose CT when possible (93.1% sensitivity, 96.6% specificity) 1

Stone analysis at least once when available, as composition directs specific preventive measures. 1, 3

Conservative Management vs. Surgical Intervention

For Ureteral Stones ≤10 mm:

Conservative management with medical expulsive therapy is appropriate if: 1, 2, 3

• Pain is well-controlled
• No sepsis present
• Adequate renal functional reserve maintained

Prescribe alpha-blockers (tamsulosin) for medical expulsive therapy, particularly for stones >5 mm in the distal ureter, as they provide the greatest benefit in this setting. 1, 2, 3

Maximum duration: 4-6 weeks from initial presentation with mandatory periodic imaging to monitor stone position and assess for hydronephrosis. 1, 2, 3

Surgical Treatment Algorithm by Stone Location and Size:

Distal ureteral stones >10 mm: Ureteroscopy is first-line surgical treatment. 1, 2

Distal ureteral stones <10 mm: Both ureteroscopy and shock wave lithotripsy (SWL) are acceptable options, though ureteroscopy yields significantly higher stone-free rates with slightly higher complication rates. 1, 2

Proximal ureteral stones (any size): Ureteroscopy is first-line surgical modality. 1

Renal stones <20 mm (pelvis, upper/middle calyx): Flexible ureteroscopy (fURS) and SWL are first-line treatments. 1

Renal stones >20 mm (any location): Percutaneous nephrolithotomy (PCNL) is first-line treatment. 1

Lower pole stones <10 mm: fURS or SWL as primary treatment. 1

Lower pole stones 10-20 mm: fURS and PCNL are suggested options. 1

Staghorn calculi: PCNL-based combination therapy is treatment of choice; SWL monotherapy should not be used. 1

Open/laparoscopic/robotic surgery should not be offered as first-line therapy except in rare cases of anatomic abnormalities with large/complex stones or those requiring concomitant reconstruction. 1

Stone Type-Specific Medical Management

Calcium Stones:

Offer thiazide diuretics (hydrochlorothiazide 25 mg twice daily or 50 mg once daily, chlorthalidone 25 mg once daily, or indapamide 2.5 mg once daily) to patients with high urinary calcium and recurrent stones. 1, 3

Offer potassium citrate to patients with low urinary citrate and recurrent calcium stones. 1, 3

Counsel patients to:

• Increase fluid intake targeting urine output ≥2.5 liters daily 1, 3
• Maintain normal dietary calcium intake (1000-1200 mg/day from food sources, not supplements) 1, 3
• Limit sodium intake to ≤2300 mg/day 1
• Limit oxalate-rich foods if hyperoxaluria present 1
• Limit animal protein to 0.8-1.0 g/kg body weight/day 1

Uric Acid Stones:

Potassium citrate is first-line therapy to alkalinize urine to pH ~6.0, as most patients have low urinary pH rather than hyperuricosuria as the predominant risk factor. 1, 3

Do not routinely offer allopurinol as first-line therapy, as reduction of urinary uric acid will not prevent stones in those with unduly acidic urine. 1, 3

Oral chemolysis with alkalinization using citrate or sodium bicarbonate (target pH 7.0-7.2) is strongly recommended and achieves success in approximately 80.5% of cases. 1, 2

Cystine Stones:

First-line therapy includes: 1, 3

• Increased fluid intake (often ≥4 liters/day to achieve urine volume >2.5 L/day)
• Sodium restriction (≤2300 mg/day)
• Protein restriction (0.8-1.0 g/kg body weight/day)
• Urinary alkalinization with potassium citrate (target pH 7.0)

Offer cystine-binding thiol drugs (tiopronin preferred over d-penicillamine due to fewer adverse events) if unresponsive to dietary modifications and urinary alkalinization, or with large recurrent stone burdens. 1, 3

Struvite (Infection) Stones:

Complete stone removal is essential as residual fragments serve as nidus for recurrent infection. 1

Offer long-term suppressive antibiotics if stone formation persists after removal. 1

Consider urease inhibitor acetohydroxamic acid (AHA) in patients at increased risk for recurrence, though extensive side effect profile may limit use. 1

Surgical Procedure Considerations

Use a safety guidewire for most endoscopic procedures to facilitate rapid re-access if primary wire is lost and provide access in cases of injury. 1

Administer antimicrobial prophylaxis prior to stone intervention based on prior urine culture results and local antibiogram; single oral or IV dose covering gram-positive and gram-negative uropathogens within 60 minutes of procedure. 1

Do not routinely prestent before SWL, as it provides no benefit and causes frequent stent-related symptoms. 1, 2

Prescribe alpha-blockers after SWL to facilitate passage of stone fragments. 1

Abort stone removal procedures if purulent urine or signs of sepsis develop intraoperatively. 1

Follow-Up and Recurrence Prevention

Obtain 24-hour urine specimen within six months of initiating treatment to assess response to dietary/medical therapy. 1

After initial follow-up, obtain 24-hour urine specimen annually or more frequently depending on stone activity to assess adherence and metabolic response. 1

Obtain periodic blood testing to assess for adverse effects in patients on pharmacological therapy (thiazides may cause hypokalemia and glucose intolerance; allopurinol and tiopronin may elevate liver enzymes; potassium citrate may cause hyperkalemia). 1

Obtain repeat stone analysis when available, especially in patients not responding to treatment, as stone composition may change. 1

Monitor patients with struvite stones for reinfection as they remain at increased risk for recurrence even after stone removal. 1

Common Pitfalls to Avoid

Do not use opioids as first-line analgesics—NSAIDs are superior in efficacy and avoid dependence risks. 1, 2, 3

Do not prescribe allopurinol as first-line for uric acid stones—urinary alkalinization with potassium citrate addresses the primary problem of low urinary pH. 1, 3

Do not delay admission for fever with obstruction—this represents sepsis requiring urgent drainage. 1, 2, 3

Do not offer prolonged conservative management beyond 6 weeks without reassessment and consideration of intervention. 1, 2, 3

Do not routinely stent before SWL—it provides no benefit and increases patient morbidity. 1, 2

Avoid NSAIDs in patients with significantly reduced glomerular filtration rate without careful monitoring, as they may further impact renal function. 1, 2

Do not recommend calcium restriction—normal dietary calcium intake (1000-1200 mg/day) is protective, while calcium supplements may increase stone risk. 1, 3