What are the European Association of Urology (EAU) guidelines for managing recurrent kidney stones?

European Association of Urology (EAU) Guidelines for Managing Recurrent Kidney Stones

The EAU guidelines recommend a comprehensive approach to managing recurrent kidney stones that includes increased fluid intake, dietary modifications, and targeted pharmacological interventions based on stone type and metabolic abnormalities. 1, 2

General Preventive Measures

• Fluid intake should be increased to achieve a urine volume of at least 2-2.5 L per day, which is essential for preventing all types of kidney stones 1, 3
• The SipIT intervention with semi-automated tracking via mobile apps and connected water bottles can help patients meet fluid intake goals, especially those with documented low urine production (<2 L/day) 4
• Dietary sodium restriction to 100 mEq (2,300 mg) or less daily is recommended to enhance the efficacy of medications and reduce stone formation risk 2, 3
• Maintaining normal body weight is important as obesity increases the risk of kidney stone formation 3, 5

Stone-Specific Management

Calcium Stones

• Thiazide diuretics are recommended for patients with high or relatively high urine calcium and recurrent calcium stones 6, 1

  • Effective dosages include hydrochlorothiazide (25 mg twice daily or 50 mg once daily), chlorthalidone (25 mg once daily), or indapamide (2.5 mg once daily) 6
  • Potassium supplementation may be needed when thiazides are prescribed 6

• Potassium citrate therapy (30-80 mEq per day divided into 3-4 doses) is indicated for patients with:

  • Low or relatively low urinary citrate 6, 7
  • Normal citrate but low urinary pH 6, 7
  • Calcium phosphate stones with hypocitraturia 6
  • Potassium citrate is preferred over sodium citrate as sodium can increase urine calcium excretion 6, 2

• Allopurinol should be offered to patients with recurrent calcium oxalate stones who have hyperuricosuria and normal urinary calcium 6, 1

  • Hyperuricemia is not a required criterion for allopurinol therapy 6

Uric Acid Stones

• Potassium citrate is the first-line therapy for uric acid stones to raise urinary pH to approximately 6.0 6, 1
• Allopurinol should not be routinely offered as first-line therapy as most patients have low urinary pH rather than hyperuricosuria as the predominant risk factor 6, 1

Cystine Stones

• High fluid intake of at least 4 liters per day is particularly important to decrease urinary cystine concentration below 250 mg/L 6
• Dietary sodium and protein restriction should be advised as lower sodium intake reduces cystine excretion 6
• Potassium citrate should be offered to raise urinary pH to approximately 7.0 6, 2
• Cystine-binding thiol drugs, such as tiopronin, should be offered to patients unresponsive to dietary modifications and urinary alkalinization 6, 1
  • Tiopronin is preferred over d-penicillamine due to better efficacy and fewer adverse events 1

Struvite Stones

• Struvite stones occur as a consequence of urinary infection with urease-producing organisms 6
• An aggressive medical approach is required to mitigate the risk of recurrence or progression 6
• Urease inhibitors (acetohydroxamic acid or AHA) may be beneficial, though side effects may limit use 6, 1

Monitoring and Follow-up

• 24-hour urine specimen should be obtained within six months of initiating treatment to assess response to therapy 1
• Annual 24-hour urine collections are recommended for ongoing monitoring, with more frequent testing depending on stone activity 1

Common Pitfalls and Caveats

• Dietary calcium restriction should be avoided as it can worsen stone formation 1, 3
• Combination therapy may be necessary for patients with multiple metabolic abnormalities 1, 7
• Inadequate fluid intake remains a major risk factor for stone recurrence regardless of pharmacological intervention 1, 8
• Medications such as protease inhibitors, certain antibiotics, and some diuretics can increase the risk of kidney stones 9