What are the medical management options for urolithiasis?

Medical Management of Urolithiasis

Medical management of urolithiasis centers on three pillars: acute pain control with NSAIDs as first-line therapy, medical expulsive therapy with alpha-blockers for stones >5mm, and long-term prevention strategies tailored to stone composition including increased fluid intake, thiazide diuretics for hypercalciuria, and alkaline citrates for hypocitraturia. 1

Acute Management of Renal Colic

Pain Control

• NSAIDs (diclofenac, ibuprofen, or metamizole) are the first-line analgesics for renal colic, demonstrating superior efficacy in controlling pain and reducing the need for additional analgesia compared to opioids 1, 2
• Use the lowest effective dose of NSAIDs to minimize cardiovascular and gastrointestinal risks, particularly in patients with reduced glomerular filtration rate 1
• Opioids (hydromorphone, pentazocine, or tramadol) should be reserved as second-line agents only when NSAIDs are contraindicated or insufficient; avoid pethidine 1, 2

Emergency Situations Requiring Urgent Intervention

• Immediate decompression via percutaneous nephrostomy or ureteral stenting is mandatory before definitive treatment in cases of: 1, 2
  • Sepsis with obstructing stone
  • Anuria in an obstructed kidney
  • Purulent urine with obstruction

Medical Expulsive Therapy (MET)

Indications and Efficacy

• Alpha-blockers (tamsulosin) are recommended as first-line medical expulsive therapy for ureteral stones, particularly those >5mm in the distal ureter 1, 3
• MET increases stone passage rates by 29% compared to control patients (77.3% vs 54.4% with placebo for distal stones <10mm) 1, 3
• MET reduces stone passage time and limits pain episodes 1

Patient Selection Criteria

• Patients must have well-controlled pain, no clinical evidence of sepsis, and adequate renal function when attempting spontaneous passage with MET 1
• Counsel patients that alpha-blockers are used "off-label" for this indication 3
• Most stones that will pass spontaneously do so within approximately 17 days (range 6-29 days) 3

When to Abandon Conservative Management

• If observation with MET is unsuccessful after 4-6 weeks, definitive stone treatment should be offered 3
• Immediate intervention is warranted if: 3
  • Uncontrolled pain despite adequate analgesia
  • Signs of infection or sepsis develop
  • Development of obstruction or significant hydronephrosis

Long-Term Prevention Strategies by Stone Type

Universal Recommendations for All Stone Formers

• Increase fluid intake to achieve urine output of at least 2.5 liters daily 4, 1, 5
• Obtain detailed medical and dietary history, serum chemistries, and urinalysis for initial evaluation 4
• Perform stone analysis for all first-time stone formers to guide targeted treatment 1, 3
• Follow-up with 24-hour urine collections within 6 months (AUA/CUA) or 8-12 weeks (EAU/UAA) to assess response to therapy 4, 1

Calcium Stone Formers (Most Common: >80% of Cases)

Dietary Modifications

• Maintain normal dietary calcium intake of 1,000-1,200 mg daily—do not restrict calcium as this paradoxically increases stone risk 4, 1, 2
• Restrict sodium intake to less than 2,300 mg daily (AUA/CUA) or less than 3,000-5,000 mg daily (EAU/UAA) 4
• Limit animal protein intake 4

Pharmacological Management Based on Metabolic Abnormalities

For Hypercalciuria:

• Thiazide diuretics are strongly recommended as first-line therapy 4, 1, 5

For Hypocitraturia:

• Alkali citrate or sodium bicarbonate is recommended as first-line therapy 4, 1
• The EAU specifically highlights sodium bicarbonate as a viable option, though there is theoretical concern about possible increase in urinary calcium 4

For Hyperuricosuria with Calcium Stones:

• Allopurinol is recommended by AUA, CUA, and EAU 4, 1
• Febuxostat is recommended as a second-line agent by EAU, but the FDA issued a safety alert in 2019 regarding increased risk of cardiac death compared to allopurinol—avoid febuxostat as first-line 4, 1

For Calcium Phosphate Stones:

• Hypercalciuric patients should receive thiazide diuretics 4
• If urinary pH is high, acidify urine with L-Methionine 4

For Recurrent Calcium Stone Formers Without Identifiable Metabolic Abnormalities:

• The AUA uniquely recommends empiric therapy with thiazide and/or citrate 4

Uric Acid Stone Formers

First-Line Therapy

• Urinary alkalinization with alkaline citrates to achieve urine pH 6.2-7.5 is the standard of care 4, 1, 5
• This is recommended almost universally by all guidelines 4

Role of Allopurinol

• The AUA specifically recommends against routine use of allopurinol as first-line therapy for uric acid stone formers 4
• In contrast, the EAU supports allopurinol as first-line treatment in the presence of hyperuricosuria in uric acid stone formers 4
• Given this divergence, prioritize urinary alkalinization first; reserve allopurinol for hyperuricosuric patients or those refractory to alkalinization 4, 5

Cystine Stone Formers

Conservative Management

• Increase fluid intake to achieve urine output of at least 3 liters daily 4, 1
• Urinary alkalinization to achieve urine pH 7.0-7.5 4, 1
• Restrict sodium and animal protein ingestion 5

Pharmacological Therapy

• If refractory to alkalinization, initiate thiol-binding agents (tiopronin or D-penicillamine) 4, 5
• These agents are reserved for patients where conservative approach fails due to significant side effects 5

Struvite Stone Formers

• Optimal management is complete surgical stone removal 5
• Acetohydroxamic acid may be offered only after surgical options have been exhausted for patients with residual stones, but it has many side effects and should be used with extreme caution 5

Monitoring and Follow-Up Protocol

Metabolic Monitoring

• Perform follow-up 24-hour urine collections within 8-12 weeks after initiating therapy to assess response 4, 1
• Conduct periodic blood tests to monitor for adverse effects of pharmacological therapy 4, 1

Imaging Surveillance

• Regular imaging studies to assess for stone growth or new stone formation, though specific timing and modality are not universally defined 4, 1
• Non-contrast CT is the gold standard for stone assessment when intervention is being considered 1, 2

Critical Pitfalls to Avoid

Dietary Misconceptions

• Never restrict dietary calcium—this increases oxalate absorption and stone risk 2
• Avoid excessive vitamin C and vitamin D supplementation 2

Medication Safety

• Monitor renal function carefully when using NSAIDs in patients with low glomerular filtration rate 1, 2
• Be aware of febuxostat's cardiac mortality risk compared to allopurinol 4, 1

Infection Management

• Never delay urgent decompression if infection is suspected with obstruction—this is a urological emergency 2, 3
• If purulent urine is encountered during endoscopic intervention, abort the procedure, establish drainage, and continue antibiotic therapy 3

Treatment Selection

• Electrohydraulic lithotripsy should not be used as first-line for intra-ureteral lithotripsy due to high risk of ureteral perforation 2
• Recognize that approximately 50% of recurrent stone-formers experience only one recurrence, while 10% have highly recurrent disease requiring more aggressive prevention 1