Kidney Stones (Nephrolithiasis): Metaphylaxis in Uric Acid Stones (Urate Stones)

Therapeutic target

Prevention of stone recurrence (recurrence of urate stones).

Reduction of risk factors

Behavioral risk factors
- Dehydration (dehydration of the body due to fluid loss or lack of fluid intake).
- High-protein and high-purine diet (meat-based diet including offal, herring, mackerel; fasting).
- Overweight or obesity
Disease-related risk factors
- Hyperchloremic metabolic acidosis due to chronic diarrhea (diarrhea) or hyperkalemic renal tubular acidosis (RTA) type IV.
- Hyperuricemia (gout)
- Metabolic syndrome (deficiency of the urinary buffer ammonia, no systemic acid-base disorder).
- Myeloproliferative syndromes (group of malignant blood disorders).
- Tumor lysis syndrome (TLS) – potentially life-threatening condition that occurs when tumors rapidly disintegrate (usually with chemotherapeutic treatment)
Drugs
- Chemotherapies due tomalignant (malignant) tumors.

Nutritional therapy

Fluid intake: 2.5-3 l/day
Alkaline-rich, alkalizing diet with potatoes, vegetables, salads, legumes and fruits; dietary supplements with alkalizing (basic) mineral compounds potassium citrate, magnesium citrate and calcium citrate, as well as vitamin D and zinc (zinc contributes to normal acid-base balance).
Limit protein intake (in hyperuricemia to 0.8 g/kg body weight / day).
Purine intake (meat, fish and seafood) per day to 300-500 mg of uric acid formed limit (see below: purines / uric acid – food).
If overweight or obese: participation in a medically supervised obesity program.

Active substances of metaphylaxis

Potassium citrate, magnesium citrate and calcium citrate for urinary alkalinization (measure urine pH before each intake; see also under daily profile of urine pH, measurement protocol).
Allopurinol, febuxostat (xanthine oxidase inhibitors).

Agents of prophylaxis of tumor lysis syndrome (TLS).