From the Research
A high-dose intravenous (IV) infusion of vitamin C (50 grams) can increase the risk of kidney stone formation in patients prone to uric acid stones, and therefore, such patients should be cautious with this treatment. Vitamin C (ascorbic acid) is metabolized to oxalate in the body, and high doses can significantly increase urinary oxalate levels 1. For patients with a history of uric acid stones or risk factors for stone formation, this oxalate load can promote stone development or growth of existing stones. The risk is particularly concerning at doses above 2 grams daily, making a 50-gram IV infusion potentially problematic.
Key Considerations
- Patients receiving high-dose vitamin C therapy should maintain excellent hydration (at least 2-3 liters of fluid daily) to help reduce the concentration of oxalate in the urine.
- Consider urinary alkalinization if appropriate, as acidic urine is a significant risk factor for uric acid stone formation, and alkalinization can help prevent stone formation 2, 3.
- Patients should have their urinary oxalate levels monitored to assess the risk of stone formation.
- The kidney stone risk must be weighed against any potential benefits of high-dose vitamin C therapy, especially in patients with existing kidney disease, history of stones, or genetic predisposition to oxalate metabolism disorders.
Management of Uric Acid Stones
- Urinary alkalization with potassium citrate or sodium bicarbonate is a highly effective treatment for uric acid stones, resulting in dissolution of existing stones and prevention of recurrence 2, 3, 1.
- Potassium citrate can increase urinary pH, decrease urinary saturation of calcium oxalate, and inhibit new stone formation 4, 3.
- Patients with uric acid stones should be managed with urinary alkalinization and other preventive measures to reduce the risk of stone recurrence.