What are the treatment options for a patient presenting with kidney stones?

Kidney Stone Treatment

Increase fluid intake to achieve at least 2.5 liters of urine output daily—this is the single most powerful intervention for both acute management and prevention of recurrence, and should be combined with stone-specific pharmacological therapy based on metabolic evaluation. 1, 2

Immediate Management Approach

Universal First-Line Intervention

• Prescribe aggressive hydration targeting minimum urine output of 2.5 liters daily for all stone types 1, 3
• For cystine stones specifically, push fluid intake even higher to at least 4 liters daily to decrease urinary cystine concentration below 250 mg/L 2, 3
• Coffee, tea, wine, and orange juice are associated with lower stone risk, while sugar-sweetened beverages increase risk 1

Essential Diagnostic Workup

Metabolic Evaluation

• Obtain comprehensive 24-hour urine collection analyzing total volume, pH, calcium, oxalate, uric acid, citrate, sodium, potassium, and creatinine in all recurrent stone formers 1, 3
• Perform stone analysis when available to guide specific preventive measures 1, 3
• Check serum intact parathyroid hormone if primary hyperparathyroidism is suspected 1, 3
• Review imaging to quantify stone burden and identify high-risk patients 1, 3

Stone-Type-Specific Pharmacological Management

Calcium Stones with Hypercalciuria

• Prescribe thiazide diuretics as first-line therapy: hydrochlorothiazide 25 mg twice daily or 50 mg once daily, chlorthalidone 25 mg once daily, or indapamide 2.5 mg once daily 1, 3
• Continue dietary sodium restriction to 2,300 mg (100 mEq) daily to maximize the hypocalciuric effect 1, 3
• Maintain normal dietary calcium intake of 1,000-1,200 mg/day—do not restrict calcium as a 5-year RCT showed 51% lower recurrence with normal calcium (1,200 mg/day) versus low calcium (400 mg/day) diet 1
• Avoid calcium supplements as they increase stone risk by 20% 1

Calcium Stones with Hypocitraturia

• Prescribe potassium citrate therapy to increase urinary citrate, which inhibits calcium stone formation 1, 2, 3
• Prospective RCTs demonstrate reduced risk of recurrent calcium stones with potassium citrate 1
• Use potassium citrate, not sodium citrate, as sodium load increases urinary calcium excretion 2, 3

Calcium Oxalate Stones with Hyperuricosuria

• Prescribe allopurinol for patients with hyperuricosuria (>800 mg/day) and normal urinary calcium 1, 3
• A prospective RCT demonstrated reduced recurrence in this specific population 1
• Critical pitfall: Do not use allopurinol as first-line for uric acid stones without addressing urinary pH 2

Uric Acid Stones

• Prescribe potassium citrate as first-line therapy to increase urinary pH to approximately 6.0, enhancing uric acid solubility 2, 3
• Most patients have low urinary pH rather than hyperuricosuria, making pH correction the primary target 3
• Allopurinol is not first-line unless urinary pH is already optimized 2

Cystine Stones

• Prescribe potassium citrate to raise urinary pH to approximately 7.0 2, 3
• If unresponsive to dietary modifications and urinary alkalinization, prescribe tiopronin (alpha-mercaptopropionylglycine) 2
• Tiopronin is preferred over d-penicillamine due to better efficacy and fewer adverse events 2

Struvite Stones

• Complete surgical removal coupled with appropriate antibiotic therapy is necessary 4
• Acetohydroxamic acid (AHA) may be considered as a urease inhibitor in high-risk patients when surgery is not feasible, though extensive side effects may limit use 2, 3

Calcium Phosphate Stones

• Prescribe potassium citrate if hypocitraturia is present, as citrate is a potent inhibitor of calcium phosphate crystallization 3
• Exercise caution with excessive alkalinization, as calcium phosphate solubility decreases at higher pH 3

Dietary Management Algorithm

For All Stone Types

• Maintain normal dietary calcium intake of 1,000-1,200 mg/day 1, 3
• Limit sodium intake to 2,300 mg daily 1, 3
• Consume ample fruits and vegetables to counterbalance acid load 3

Follow-Up and Monitoring Protocol

Short-Term Monitoring

• Obtain 24-hour urine specimen within 6 months of initiating treatment to assess response 1, 2, 3
• Monitor for hypokalemia with thiazides and hyperkalemia with potassium citrate 1, 2, 3

Long-Term Monitoring

• Perform annual 24-hour urine collections for ongoing monitoring, with more frequent testing depending on stone activity 2
• Obtain repeat stone analysis when available, especially in patients not responding to treatment 2
• Periodic blood testing is necessary to monitor for adverse effects in patients on pharmacological therapy 2, 3

Critical Pitfalls to Avoid

• Never restrict dietary calcium—this paradoxically increases stone risk 1
• Never use sodium citrate instead of potassium citrate—sodium increases urinary calcium excretion 2, 3
• Never prescribe allopurinol for uric acid stones without first addressing urinary pH—pH correction is primary 2
• Never fail to monitor electrolytes—thiazides cause hypokalemia and potassium citrate causes hyperkalemia 1, 2, 3
• Never over-alkalize urine in calcium phosphate stone formers—this decreases calcium phosphate solubility 3