From the Guidelines
The treatment for uric acid kidney stones focuses on increasing urine pH and reducing uric acid levels, with potassium citrate being the primary medication used to alkalinize the urine, aiming for a urine pH between 6.5 and 7.0, as recommended by the American College of Physicians guideline 1. Patients should increase fluid intake to at least 2-3 liters daily to maintain dilute urine.
- Potassium citrate (typically 10-20 mEq taken 2-3 times daily) is used to alkalinize the urine.
- For patients with recurrent stones or high uric acid production, allopurinol (starting at 100 mg daily, potentially increasing to 300 mg daily) may be prescribed to reduce uric acid production, as supported by the American College of Physicians guideline 1. Dietary modifications are also important, including:
- Limiting purine-rich foods like red meat, organ meats, and shellfish
- Increasing fruits and vegetables
- Reducing sodium intake to decrease urinary calcium excretion Regular pH monitoring using test strips is recommended to ensure the urine remains appropriately alkaline. These treatments work because uric acid stones form in acidic urine (pH below 5.5), and by raising the pH, the uric acid becomes more soluble and less likely to crystallize. Allopurinol inhibits xanthine oxidase, the enzyme responsible for uric acid production, thereby reducing the amount of uric acid available to form stones. However, clinicians should not routinely offer allopurinol as first-line therapy to patients with uric acid stones, as most patients with uric acid stones have low urinary pH rather than hyperuricosuria as the predominant risk factor, as stated in the medical management of kidney stones: AUA guideline 1.
From the FDA Drug Label
1.3 Uric Acid Lithiasis with or without Calcium Stones Potassium Citrate is indicated for the management of Uric acid lithiasis with or without calcium stones
Allopurinol tablets are indicated in:
- the management of patients with signs and symptoms of primary or secondary gout (acute attacks, tophi, joint destruction, uric acid lithiasis, and/or nephropathy).
The treatment for uric acid kidney stones includes:
- Potassium Citrate: to manage uric acid lithiasis with or without calcium stones 2
- Allopurinol: to manage patients with signs and symptoms of primary or secondary gout, including uric acid lithiasis 3 3 Key points:
- Potassium Citrate is used to manage uric acid kidney stones by increasing urinary pH and citrate levels
- Allopurinol is used to reduce serum and urinary uric acid levels by inhibiting the formation of uric acid
From the Research
Treatment Options for Uric Acid Kidney Stones
- Uric acid stones can be treated with pharmacotherapy, extracorporeal shock wave lithotripsy, or minimally invasive procedures such as ureteroscopy, depending on the size of the stone and the presence of any urinary tract obstruction or infection 4.
- Alkalization of urine is an effective therapy for preventing uric acid crystallization and can be achieved with potassium citrate or sodium bicarbonate 5, 6.
- Medical treatment with urinary alkalization can result in dissolution of existing stones and prevention of recurrence, and is considered the cornerstone of treatment for uric acid kidney stones 6, 7.
Pharmacological Treatment
- Potassium citrate is a commonly used medication for the treatment of uric acid kidney stones, and has been shown to be effective in increasing urinary pH and reducing the risk of stone recurrence 5, 7.
- Alkaline citrate (Uralyt-U) is another medication that has been used for oral chemolysis of uric acid stones, and has been shown to be effective in dissolving stones in some patients 8.
- Allopurinol may be combined with alkaline citrate in patients with hyperuricemia to enhance the effectiveness of treatment 8.
Minimally Invasive Procedures
- Ureteroscopy and other minimally invasive procedures may be reserved for larger stones (diameter ≥2 cm) or patients with concomitant urinary tract obstruction and/or infections 4.
- Extracorporeal shock wave lithotripsy may be used in combination with oral chemolysis to shorten the period to be stone-free 8.