What is the treatment for kidney stones?

Treatment of Kidney Stones

For acute kidney stone pain, administer NSAIDs (specifically intramuscular diclofenac 75 mg) as first-line therapy, reserve opioids only when NSAIDs are contraindicated, and initiate medical expulsive therapy with tamsulosin for stones >5 mm in the distal ureter while pursuing conservative management for uncomplicated stones up to 10 mm for 4-6 weeks. 1, 2

Acute Pain Management

• NSAIDs are superior to opioids for renal colic because they reduce ureteral smooth muscle tone and spasm, have fewer side effects, and carry lower risk of dependence 2
• Intramuscular diclofenac 75 mg should provide pain relief within 30 minutes 2
• Other effective NSAIDs include ibuprofen and metamizole 2
• Opioids (hydromorphine, pentazocine, or tramadol) should be reserved as second-choice analgesics only when NSAIDs are contraindicated 2
• Avoid pethidine due to high rates of vomiting and need for additional analgesia 2
• Failure to respond to analgesia within one hour requires immediate hospital admission 2

Emergency Indications Requiring Urgent Intervention

• Fever with obstructed kidney requires urgent decompression via percutaneous nephrostomy or ureteral stenting 2
• Anuria mandates emergency intervention 2
• Shock or fever requires immediate hospital admission 2
• Abrupt recurrence of severe pain after initial relief requires immediate hospital admission 2

Initial Diagnostic Workup

• Obtain detailed medical and dietary history to identify conditions, habits, or medications that predispose to stone disease 3, 1
• Order serum chemistries including electrolytes, calcium, creatinine, and uric acid to identify underlying metabolic conditions 3, 1, 2
• Perform urinalysis with both dipstick and microscopic evaluation to assess urine pH, indicators of infection, and identify crystals pathognomonic of stone type 3, 1, 2
• Obtain urine culture if urinalysis suggests infection or patient has history of recurrent UTIs 3, 1, 2
• Renal ultrasonography is the recommended first-line imaging modality to quantify stone burden and guide treatment decisions 1, 2
• Non-contrast CT can be used if ultrasound is insufficient 2

Conservative Management vs. Intervention Algorithm

Conservative management is appropriate for uncomplicated ureteral stones up to 10 mm (AUA guideline) or up to 6 mm (EAU guideline) 1, 2

• Medical expulsive therapy (MET) with alpha-blockers (tamsulosin) should be offered, particularly for stones >5 mm in the distal ureter 1, 2
• Maximum duration of conservative treatment is 4-6 weeks from initial presentation 1, 2
• For stones that fail to pass spontaneously after this period, intervention is required 1
• Instruct patient to void urine into a container or through a tea strainer to catch any passed stone for analysis 2
• Stone analysis should be performed for all first-time stone-formers to guide prevention strategies 2

Supportive Care During Conservative Management

• Increase fluid intake to achieve urine output of at least 2.5 liters daily to promote stone passage 2, 4, 5
• Coffee, tea, wine, and orange juice are associated with lower stone risk, while sugar-sweetened beverages should be avoided 2
• Telephone follow-up one hour after initial assessment to verify pain control 2
• Imaging studies within 7 days if stone has not passed to reassess stone burden 2

Medical Management Based on Stone Type

Calcium Stones

• For hypercalciuria: offer thiazide diuretics (hydrochlorothiazide 25 mg twice daily or 50 mg once daily) 1, 2, 4
• Dietary sodium restriction should be advised to maximize the hypocalciuric effect of thiazides 4
• For hypocitraturia: offer potassium citrate therapy to increase urinary pH and inhibit stone formation 1, 2, 4
• For hyperuricosuria with calcium oxalate stones: allopurinol is indicated 6
• For absorptive hyperoxaluria: low oxalate diet and increased dietary calcium intake are recommended 6

Uric Acid Stones

• Potassium citrate is first-line therapy to raise urinary pH to approximately 6.0, enhancing uric acid solubility 1, 4
• Oral chemolysis with alkalinization using citrate or sodium bicarbonate (target pH 7.0-7.2) 2
• Allopurinol should not be prescribed as first-line therapy without addressing urinary pH 4

Cystine Stones

• First-line therapy includes increased fluid intake (target at least 4 liters per day to decrease urinary cystine concentration below 250 mg/L), restriction of sodium and protein intake, and urinary alkalinization 1, 4
• Potassium citrate should be offered to raise urinary pH to approximately 7.0 1, 4
• Cystine-binding thiol drugs, such as tiopronin, should be offered to patients unresponsive to dietary modifications and urinary alkalinization 4
• Tiopronin is preferred over d-penicillamine due to better efficacy and fewer adverse events 4

Brushite Stones

• For hypocitraturia or elevated urine pH: potassium citrate is first-line pharmacological therapy 1
• Potassium citrate is preferred over sodium citrate as the sodium load in the latter may increase urine calcium excretion 1
• Thiazide diuretics should be offered to brushite stone formers with hypercalciuria 1
• The combination of potassium citrate and thiazide diuretics can be used for patients with persistent stone formation 1

Struvite Stones

• Complete surgical removal coupled with appropriate antibiotic therapy is necessary 6
• Urease inhibitors (acetohydroxamic acid) may be beneficial, though side effects may limit use 4

Dietary Recommendations for Prevention

• Maintain fluid intake of 2.5-3.0 L/day to achieve urine output >2.0-2.5 L/day 5
• Sufficient calcium intake at 1000-1200 mg/day (dietary, not supplemental) 5
• Limit sodium to 2-3 g/day or 3-5 g/day of sodium chloride 5
• Limit oxalate-rich foods 5
• Avoid vitamin C and vitamin D supplements 5
• Limit animal proteins to 0.8-1.0 g/kg body weight/day but increase plant proteins in patients with calcium and uric acid stones 5
• Increase proportion of citrus fruits 5
• Maintain normal body mass index and regular exercise 7

Follow-Up and Monitoring Protocol

• A single 24-hour urine specimen for stone risk factors should be obtained within six months of initiating treatment to assess response to dietary and/or medical therapy 1, 4
• After initial follow-up, a single 24-hour urine specimen should be obtained annually or with greater frequency, depending on stone activity 1, 4
• Periodic blood testing should be performed to assess for adverse effects in patients on pharmacological therapy (such as hypokalemia with thiazides or hyperkalemia with potassium citrate) 1, 4
• Repeat stone analysis should be obtained when available, especially in patients not responding to treatment 1, 4

Critical Pitfalls to Avoid

• Do not use opioids as first-line therapy - NSAIDs are superior and avoid dependence risks 2
• Do not delay admission for patients with fever and obstruction - this represents a urologic emergency requiring immediate drainage 2
• Do not prescribe oral or rectal analgesics as primary therapy in acute settings - intramuscular route is preferred 2
• Do not restrict dietary calcium - this may paradoxically increase stone risk by increasing intestinal oxalate absorption 2, 8
• Do not use supplemental calcium rather than dietary calcium, as supplemental calcium may be associated with increased risk of stone formation 1
• Do not prescribe allopurinol as first-line therapy for uric acid stones without addressing urinary pH 1, 4
• Do not use sodium citrate instead of potassium citrate as it may increase urine calcium excretion 1, 4
• Do not neglect to address underlying metabolic abnormalities that contribute to stone formation 1