From the Guidelines
To prevent calcium oxalate kidney stones, increase your fluid intake to at least 2.5 liters daily, as recommended by the American Urological Association guideline 1. This is based on the strongest and most recent evidence, which suggests that high fluid intake is a critical component of stone prevention.
Key Recommendations
- Increase fluid intake to at least 2.5 liters daily to dilute urine and reduce crystal formation.
- Limit sodium intake to less than 2,300 mg daily, as high sodium increases calcium excretion, as supported by the American College of Physicians guideline 1.
- Maintain normal calcium intake (1,000-1,200 mg daily) from dietary sources rather than supplements, as adequate calcium binds to oxalate in the gut, preventing its absorption, as shown in a randomized controlled trial 1.
- Limit animal protein consumption to 0.8-1 g/kg body weight daily.
Medical Management
For medical management, your doctor may prescribe:
- Potassium citrate (typically 10-15 mEq twice daily) to increase urine pH and citrate levels, which inhibit stone formation, as supported by moderate-quality evidence from several trials 1.
- Thiazide diuretics like hydrochlorothiazide (12.5-50 mg daily) may be recommended for those with high urinary calcium, as shown in several fair-quality trials 1. These strategies work by addressing the main factors in calcium oxalate stone formation: high urinary calcium, high urinary oxalate, low urinary citrate, and low urine volume.
Monitoring Progress
Regular follow-up with urinalysis and possibly 24-hour urine collections can help monitor your progress and adjust prevention strategies as needed.
From the FDA Drug Label
The effect of oral Potassium Citrate therapy in a non-randomized, non-placebo controlled clinical study of five men and four women with calcium oxalate/calcium phosphate nephrolithiasis and documented incomplete distal renal tubular acidosis was examined Potassium Citrate therapy was associated with inhibition of new stone formation in patients with distal tubular acidosis. All patients had a reduced stone formation rate. Over the first 2 years of treatment, the on-treatment stone formation rate was reduced from 13±27 to 1±2 per year. The stone-passage remission rate was 67%. The dose of Potassium Citrate ranged from 30 to 100 mEq per day, and usually was 20 mEq administered orally 3 times daily. Treatment that included Potassium Citrate was associated with a sustained increase in urinary citrate excretion from subnormal values to normal values (400 to 700 mg/day), and a sustained increase in urinary pH from 5.6-6.0 to approximately 6. 5. The stone formation rate was reduced in all groups as shown in Table 1.
Calcium Oxalate Stone Prevention:
- Potassium citrate can help prevent calcium oxalate stone formation by increasing urinary citrate excretion and urinary pH.
- The recommended dose of potassium citrate is 30-100 mEq per day, usually 20 mEq administered orally 3 times daily.
- Patients should also stay on a sodium restricted diet (100 mEq/day) and reduce oxalate intake.
- A moderate calcium restriction (400-800 mg/day) may be imposed on patients with hypercalciuria.
- The stone-passage remission rate with potassium citrate therapy is 67% 2.
- Allopurinol may also be used to prevent calcium oxalate stones in hyperuricosuric patients, with a recommended dose of 200-300 mg/day in divided doses or as the single equivalent 3.
From the Research
Calcium Oxalate Stone Prevention Strategies
- Increase fluid intake to achieve a urine volume of 2 l or more per day 4
- Maintain a recommended calcium intake of 800-1200 mg/day 4
- Restrict high oxalate foods 4
- Limit daily protein intake to 0.8-1 g/kg body weight/day 4
- Include essential fats and increase vegetable and fruit intake (except oxalate-rich vegetables) 4
Medical Treatment Options
- Thiazide diuretics can lower urine calcium and reduce calcium oxalate supersaturation 5, 6
- Potassium citrate therapy can increase urinary citrate and pH, and decrease calcium oxalate supersaturation 5, 7
- Alkali therapy may not be effective for calcium phosphate stone formers 5
Dietary Recommendations
- Low-salt and low-protein diet 8
- Rich in calcium and magnesium 8
- Adequate fluid intake 8, 6
- Restrict dietary sodium to reduce urine calcium 6