What are the treatment options for kidney stones?

Treatment Options for Kidney Stones

The treatment of kidney stones should be tailored to the specific stone type, with potassium citrate being the first-line therapy for uric acid and cystine stones, thiazide diuretics for calcium stones with hypercalciuria, and allopurinol for calcium oxalate stones with hyperuricosuria. 1, 2

Initial Assessment and Evaluation

• A comprehensive evaluation should include detailed medical and dietary history, serum chemistries (electrolytes, calcium, creatinine, uric acid), and urinalysis to identify underlying conditions and stone type 3, 2
• Imaging studies are essential to quantify stone burden and guide treatment decisions 2
• Stone analysis should be obtained at least once to determine composition, which guides specific treatment approaches 3, 2

Medical Management Based on Stone Type

Calcium Stones

• Thiazide diuretics should be offered to patients with high urinary calcium and recurrent calcium stones 1, 2
• Potassium citrate therapy is indicated for patients with recurrent calcium stones and low urinary citrate 1, 2
• Allopurinol should be offered to patients with recurrent calcium oxalate stones who have hyperuricosuria and normal urinary calcium 1
• For patients with calcium stones without other metabolic abnormalities or with persistent stone formation despite addressing other abnormalities, thiazide diuretics and/or potassium citrate are recommended 1

Uric Acid Stones

• Potassium citrate is the first-line therapy to raise urinary pH to approximately 6.0 1, 2
• 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 1, 2

Cystine Stones

• First-line therapy includes increased fluid intake, restriction of sodium and protein intake, and urinary alkalinization with potassium citrate to achieve a urine pH of 7.0 1, 2
• Cystine-binding thiol drugs, such as alpha-mercaptopropionylglycine (tiopronin), should be offered to patients unresponsive to dietary modifications and urinary alkalinization, or those with large recurrent stone burdens 1

Struvite Stones

• Struvite stones occur due to urinary infection with urease-producing organisms 1
• Patients with struvite stones require aggressive medical management and may benefit from urease inhibitors 1
• These patients should be monitored for reinfection 3

Conservative Management

• Increased fluid intake is essential for all stone types to achieve urine volume of at least 2.5 liters daily 3, 4
• Medical expulsive therapy (MET) with alpha-blockers (tamsulosin) is recommended for uncomplicated ureteral stones, particularly for stones >5 mm in the distal ureter 2, 5
• Conservative management is appropriate for uncomplicated ureteral stones up to 10 mm 2, 5

Dietary Interventions

• Dietary modifications are crucial for stone prevention 6, 4:
  • Sufficient calcium intake (1000-1200 mg/day) 4
  • Limited sodium intake (2-5 g/day of sodium chloride) 4
  • Limited intake of oxalate-rich foods for calcium oxalate stone formers 4
  • Increased consumption of fruits and vegetables to counterbalance acid load 1
  • Limited animal protein intake (0.8-1.0 g/kg body weight/day) 4
  • Increased proportion of citrus fruits 4

Pharmacological Interventions

• Potassium citrate has shown effectiveness in multiple stone types:
  • For renal tubular acidosis with calcium stones, potassium citrate (60-80 mEq daily in 3-4 divided doses) was associated with inhibition of new stone formation 7
  • For hypocitraturic calcium oxalate nephrolithiasis, potassium citrate (30-100 mEq per day) increased urinary citrate excretion and reduced stone formation 7
  • For uric acid lithiasis, potassium citrate (30-80 mEq/day) significantly raised urinary pH and prevented stone recurrence 7

Surgical Interventions

• For stones that fail to pass spontaneously within 4-6 weeks, intervention is required based on stone size and location 2, 5
• Options include extracorporeal shock wave lithotripsy, percutaneous nephrolithotomy, ureteroscopy, ureteral stents, and nephrostomy tubes 5

Follow-up and Monitoring

• A single 24-hour urine specimen should be obtained within six months of initiating treatment to assess response to therapy 1, 2
• After initial follow-up, a 24-hour urine specimen should be collected annually or more frequently depending on stone activity 1, 2
• Periodic blood testing should be performed to assess for adverse effects in patients on pharmacological therapy 2

Common Pitfalls to Avoid

• Using sodium citrate instead of potassium citrate, as the sodium load may increase urine calcium excretion 1
• Prescribing allopurinol as first-line therapy for uric acid stones instead of urinary alkalinization with potassium citrate 1, 2
• Using supplemental calcium rather than dietary calcium, as supplements may increase stone formation risk 2
• Neglecting to address underlying metabolic abnormalities that contribute to stone formation 2