Treatment Options for Kidney Stones
The treatment of kidney stones should be tailored to the specific stone type, with increased fluid intake being essential for all stone types, followed by targeted pharmacological therapy based on stone composition and metabolic abnormalities. 1, 2
General Management for All Stone Types
- Increased fluid intake to achieve urine output of at least 2.5 liters daily is the cornerstone of both treatment and prevention for all kidney stone types 1, 2, 3
- A 24-hour urine specimen should be obtained to assess metabolic abnormalities and guide specific treatment approaches 2, 4
- Stone analysis should be performed at least once when available to determine stone composition and direct appropriate therapy 2
Stone-Specific Treatment Options
Calcium Stones
- Thiazide diuretics are recommended for patients with hypercalciuria and recurrent calcium stones 1, 4
- Potassium citrate therapy is indicated for patients with calcium stones and low urinary citrate 1, 4
- Dietary calcium should be maintained at normal levels (1,000-1,200 mg daily) rather than restricted, as calcium restriction may actually increase stone risk 2, 3
- Sodium intake should be limited to 2,300 mg daily to maximize the hypocalciuric effect of thiazides 1, 2
- Allopurinol should be offered to patients with calcium oxalate stones who have hyperuricosuria and normal urinary calcium 4
Uric Acid Stones
- Potassium citrate is the first-line therapy to increase urinary pH to approximately 6.0, enhancing uric acid solubility 5, 1, 4
- Allopurinol should not be routinely offered as first-line therapy for uric acid stones, as most patients have low urinary pH rather than hyperuricosuria as the predominant risk factor 5, 4
Cystine Stones
- Increased fluid intake is particularly important, with a target of at least 4 liters per day to decrease urinary cystine concentration below 250 mg/L 1, 2
- Potassium citrate should be offered to raise urinary pH to approximately 7.0 5, 1
- Cystine-binding thiol drugs, such as alpha-mercaptopropionylglycine (tiopronin), should be offered to patients unresponsive to dietary modifications and urinary alkalinization 5, 4
- Tiopronin is preferred over d-penicillamine due to better efficacy and fewer adverse events 5, 4
Struvite Stones
- Complete surgical removal coupled with appropriate antibiotic therapy is necessary 6
- Urease inhibitors (acetohydroxamic acid or AHA) may be beneficial, though side effects may limit use 5, 4
Follow-up Care
- A 24-hour urine specimen should be obtained within six months of initiating treatment to assess response to therapy 5, 1, 4
- Annual 24-hour urine collections are recommended for ongoing monitoring, with more frequent testing depending on stone activity 5, 4
- Periodic blood testing is necessary to monitor for adverse effects in patients on pharmacological therapy 5, 1
- Repeat stone analysis should be obtained when available, especially in patients not responding to treatment 5
Common Pitfalls to Avoid
- Inadequate fluid intake remains a major risk factor for stone recurrence regardless of pharmacological intervention 1, 4
- Using sodium citrate instead of potassium citrate may increase urine calcium excretion 1, 4
- Dietary calcium restriction should be avoided as it can worsen stone formation 2, 3
- Prescribing allopurinol as first-line therapy for uric acid stones without addressing urinary pH is not recommended 5, 1
- Failure to monitor for medication side effects, such as hypokalemia with thiazides or hyperkalemia with potassium citrate 5, 1