What are the treatment guidelines for kidney stones?

Treatment Guidelines for Kidney Stones

For acute kidney stone pain, NSAIDs (specifically intramuscular diclofenac 75 mg) are first-line therapy and superior to opioids, with pain relief expected within 30 minutes; for uncomplicated ureteral stones ≤10 mm, observation with medical expulsive therapy using alpha-blockers is appropriate for 4-6 weeks, while surgical intervention depends on stone size and location, with ureteroscopy preferred for most ureteral stones and percutaneous nephrolithotomy reserved for renal stones >20 mm. 1, 2

Acute Pain Management

• NSAIDs are the first-line analgesic for acute renal colic, specifically intramuscular diclofenac 75 mg, which provides superior pain control compared to opioids with fewer side effects and lower dependence risk 1, 3
• Pain relief should occur within 30 minutes of NSAID administration; if pain persists after one hour, immediate hospital admission is required 3
• Opioids (hydromorphine, pentazocine, or tramadol) should be reserved as second-line agents only when NSAIDs are contraindicated (cardiovascular disease, gastrointestinal bleeding risk, renal insufficiency, heart failure) 1, 3
• Use the lowest effective NSAID dose to minimize cardiovascular and gastrointestinal risks, and exercise caution in patients with reduced glomerular filtration rate 1
• Avoid pethidine due to high vomiting rates 1

Emergency Situations Requiring Urgent Intervention

• In cases of obstructive pyelonephritis (fever with obstruction) or anuria with obstructed kidney, urgent decompression via percutaneous nephrostomy or ureteral stenting is mandatory before definitive stone treatment 1
• Collect urine for culture before and after decompression, administer antibiotics immediately, and adjust based on culture results 1
• Delay definitive stone treatment until sepsis is resolved 1
• Patients with shock, fever, or failure to respond to analgesia within one hour require immediate hospital admission 3

Conservative Management and Medical Expulsive Therapy

Observation Criteria

• For uncomplicated ureteral stones ≤10 mm without infection or obstruction, observation with medical expulsive therapy is appropriate initial management 2, 1
• Patients must have well-controlled pain, no clinical evidence of sepsis, and adequate renal functional reserve 2, 1
• Maximum duration of conservative treatment is 4-6 weeks from initial clinical presentation 2, 1
• Mandatory periodic imaging is required to monitor stone position and assess for hydronephrosis 2, 1

Medical Expulsive Therapy

• Alpha-blockers (tamsulosin) provide the greatest benefit for distal ureteral stones >5 mm, with stone-free rates of 77.3% compared to 54.4% with placebo (OR 3.79,95% CI 2.84-5.06) 2, 1
• Patients should be counseled that medical expulsive therapy is "off-label" use and informed of potential drug side effects 2
• Alpha-blockers should also be prescribed after shock wave lithotripsy to facilitate passage of stone fragments 2

Surgical Treatment Based on Stone Characteristics

Ureteral Stones

• For distal ureteral stones >10 mm, ureteroscopy is the first-line surgical treatment 2
• For distal ureteral stones <10 mm, both ureteroscopy and shock wave lithotripsy are acceptable first-line options 2
• Ureteroscopy yields significantly higher stone-free rates than shock wave lithotripsy but has slightly higher complication rates (ureteral injury 3-6% vs 1-2%; stricture 1-4% vs 0-2%) 2
• For proximal ureteral stones, ureteroscopy is recommended as first-line treatment regardless of stone size, though shock wave lithotripsy is an equivalent option for stones <10 mm 2

Renal Stones

• Active surveillance is acceptable for asymptomatic, non-obstructing caliceal stones up to 15 mm 2
• For renal stones <10 mm (renal pelvis, upper/middle calyx), flexible ureteroscopy or shock wave lithotripsy are first-line treatments 2
• For renal stones 10-20 mm, flexible ureteroscopy is preferred, with percutaneous nephrolithotomy as an alternative option 2
• For renal stones >20 mm regardless of location, percutaneous nephrolithotomy is the first-line treatment 2

Lower Pole Stones (Special Considerations)

• For lower pole stones <10 mm, flexible ureteroscopy or shock wave lithotripsy are primary treatments 2
• For lower pole stones 10-20 mm, flexible ureteroscopy or percutaneous nephrolithotomy are recommended (shock wave lithotripsy acceptable only with favorable anatomy: broad infundibulo-pelvic angle, short infundibulum, wide infundibulum) 2

Perioperative Management

Stenting Recommendations

• Routine prestenting before shock wave lithotripsy is not recommended as it provides no benefit and causes frequent stent-related symptoms 2
• Routine stent placement after uncomplicated ureteroscopy is not recommended 2
• If a ureteral stent is placed postoperatively, prescribe alpha-blockers to reduce stent discomfort; anti-muscarinics are also an option 2
• After uncomplicated percutaneous nephrolithotomy, tubeless (without nephrostomy tube) or totally tubeless (without nephrostomy tube or ureteral stent) approaches are preferred 2

Lithotripsy Technique

• Use laser or pneumatic lithotripsy with semirigid ureteroscopes; laser lithotripsy is preferred for flexible ureteroscopy 2
• Electrohydraulic lithotripsy should not be used for ureteral stones 2
• Always use a safety wire during ureteroscopy 2
• Blind stone extraction with a basket should never be performed; intraureteral manipulations must be under direct ureteroscopic vision 2

Medical Management for Stone Prevention

Calcium Stones

• For patients with hypercalciuria and recurrent calcium stones, thiazide diuretics should be offered 2, 4
• For patients with hypocitraturia and recurrent calcium stones, potassium citrate therapy should be offered to raise urinary citrate to >320 mg/day (target 640 mg/day) 2, 4, 5
• For severe hypocitraturia (<150 mg/day), initiate potassium citrate at 60 mEq/day in divided doses with meals 5
• For mild to moderate hypocitraturia (>150 mg/day), initiate potassium citrate at 30 mEq/day in divided doses with meals 5

Uric Acid Stones

• For uric acid stones, oral chemolysis with urinary alkalinization using potassium citrate is first-line therapy, targeting urine pH 6.0-7.2 (success rate approximately 80.5%) 2, 1, 4
• Allopurinol should not be routinely offered as first-line therapy since most patients have low urinary pH rather than hyperuricosuria as the predominant risk factor 2
• Patients should monitor urine pH and adjust medication accordingly 1

Cystine Stones

• First-line therapy includes increased fluid intake (target >2.5 L/day), restriction of sodium and protein intake, and urinary alkalinization with potassium citrate 2, 4
• If dietary modifications and alkalinization fail, offer cystine-binding thiol drugs (tiopronin preferred over d-penicillamine due to fewer adverse events) 2

Struvite Stones

• Patients with struvite stones should be monitored for reinfection 2
• Urease inhibitor (acetohydroxamic acid) may be beneficial but has extensive side effect profile limiting use 2

Follow-Up and Monitoring

• Obtain a single 24-hour urine specimen for stone risk factors within 6 months of initiating treatment to assess response to dietary and/or medical therapy 2, 4
• After initial follow-up, obtain a single 24-hour urine specimen annually or more frequently depending on stone activity 2, 4
• Perform periodic blood testing to assess for adverse effects in patients on pharmacological therapy (thiazides: hypokalemia, glucose intolerance; allopurinol/tiopronin: elevated liver enzymes; potassium citrate: hyperkalemia) 2
• Obtain repeat stone analysis when available, especially in patients not responding to treatment, as stone composition may change 2

Preoperative Assessment

• Obtain noncontrast CT prior to surgical intervention to determine optimal approach; contrast-enhanced studies if collecting system anatomy needs further assessment 2
• Obtain urinalysis and/or urine culture prior to surgical intervention to rule out urinary tract infection 2
• Functional imaging studies (DTPA or MAG-3) if suspicion of significant renal function loss 2

Common Pitfalls to Avoid

• Do not use opioids as first-line therapy for acute renal colic - NSAIDs are superior and avoid dependence risks 1, 3
• Do not offer prolonged conservative management beyond 6 weeks without reassessment 2, 1
• Do not routinely place stents before shock wave lithotripsy - no benefit and causes stent-related symptoms 2
• Do not prescribe allopurinol as first-line therapy for uric acid stones - urinary alkalinization with potassium citrate is first-line 2
• Do not delay admission for patients with fever and obstruction - this represents a urologic emergency requiring immediate drainage 1, 3
• Do not use NSAIDs in patients with significantly reduced renal function without careful monitoring 1
• Do not perform blind stone extraction with a basket - always use direct ureteroscopic vision 2