What are the management options for kidney stones?

Management Options for Kidney Stones

The management of kidney stones should focus on increasing fluid intake to achieve urine output of at least 2.5 liters daily, combined with targeted dietary modifications and appropriate pharmacological therapy based on stone composition and metabolic abnormalities. 1, 2

Initial Evaluation

• Obtain stone analysis at least once when a stone is available to guide specific preventive measures 1
• Review available imaging studies to quantify stone burden and identify patients at higher risk of recurrence 1
• Perform metabolic testing with 24-hour urine collections in high-risk or interested first-time stone formers and all recurrent stone formers 1
• Analyze 24-hour urine for total volume, pH, calcium, oxalate, uric acid, citrate, sodium, potassium, and creatinine 1
• Obtain serum intact parathyroid hormone level if primary hyperparathyroidism is suspected (when serum calcium is high or high normal) 1

Dietary Management

• Increase fluid intake to achieve urine volume of at least 2.5 liters daily (cornerstone of prevention for all stone types) 1, 3
• For calcium stones:
  • Maintain normal dietary calcium intake of 1,000-1,200 mg per day (avoid calcium restriction) 1, 4
  • Limit sodium intake to 2,300 mg (100 mEq) daily to reduce urinary calcium excretion 1, 4
  • Consume ample fruits and vegetables to counterbalance acid load 1
  • Avoid sugar-sweetened beverages which increase stone risk 1
• For cystine stones:
  • Target higher fluid intake of at least 4 liters per day to decrease urinary cystine concentration below 250 mg/L 1, 2
  • Limit sodium and protein intake 1

Pharmacological Management

• For calcium stones with hypercalciuria:
  • Thiazide diuretics (hydrochlorothiazide 25 mg twice daily or 50 mg once daily, chlorthalidone 25 mg once daily, or indapamide 2.5 mg once daily) 1, 2
  • Continue dietary sodium restriction to maximize hypocalciuric effect 1
• For calcium stones with hypocitraturia:
  • Potassium citrate therapy (preferred over sodium citrate) 1, 2
• For calcium oxalate stones with hyperuricosuria:
  • Allopurinol for patients with normal urinary calcium 1, 3
• For uric acid stones:
  • Potassium citrate to increase urinary pH to approximately 6.0 2, 3
• For cystine stones:
  • Potassium citrate to raise urinary pH to approximately 7.0 2
  • Tiopronin if urinary alkalinization and adequate fluid intake are insufficient 3
• For struvite stones:
  • Complete surgical removal coupled with appropriate antibiotic therapy 3

Follow-up Care

• Obtain 24-hour urine specimen within six months of initiating treatment to assess response to therapy 2
• Monitor for adverse effects in patients on pharmacological therapy:
  • Hypokalemia with thiazides
  • Hyperkalemia with potassium citrate 2
• Continue long-term monitoring to assess stone-forming activity and stone burden 5

Common Pitfalls to Avoid

• Inadequate fluid intake is the most common preventable risk factor 2, 6
• Using sodium citrate instead of potassium citrate may increase urine calcium excretion 2
• Calcium restriction can worsen stone formation and should be avoided 4, 7
• Prescribing allopurinol as first-line therapy for uric acid stones without addressing urinary pH 2
• Failing to adjust therapy based on stone composition and specific metabolic abnormalities 1, 3