Urinary Stones (Urolithiasis): Metaphylaxis in Calcium Oxalate Stones

Therapeutic target

Prevention of stone recurrence (recurrence of urinary stones).

Therapy recommendations

Reduction of risk factors

  • Disease-related risk factors
    • Hypercalcemia (excess calcium)
    • Hypercalciuria (increased calcium excretion in the urine).
    • Hyperoxaluria (increased excretion of oxalic acid in the urine), primary as well as secondary to various diseases such as Crohn’s disease, pancreatic insufficiency (pancreatic weakness), etc.
    • Hyperparathyroidism (parathyroid hyperfunction), primary (pHPT).
    • Renal tubular acidosis (RTA) – genetic defect of the kidney (defect of H+ ion secretion in the tubular system of the kidney).
  • Medication
    • Vitamin D intoxication (e.g. due torickets prophylaxis/prevention of bone softening in children).

In about 70% of affected patients, no risk factors can be detected which is why they are counted as so-called idiopathic calcium oxalate stone formers.

Nutritional therapy

  • Fluid intake 2.5-3 l / day
  • Diet with decreased intake of sodium (increased sodium intake leads to increased loss of calcium through the kidney) and proteins (increase excretion of calcium through the urine)
  • Adjust calcium intake to 800-1,200 mg/day – restriction in the consumption of cheese and vegetables (broccoli, fennel, spinach, kale).
  • Magnesium-rich food such as rice, legumes, spinach; drink magnesium-containing mineral water (magnesium inhibits the formation of calcium oxalate stones).
  • Avoid foods rich in oxalic acid / oxalate (chard, spinach, rhubarb, block chocolate, cocoa powder).
  • 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 the normal acid-base balance).

Active substances of metaphylaxis

  • If there is a need for metabolic correction, therapy using alkali citrates or sodium bicarbonate is considered the first choice.

Surgical therapy

  • Parathyroidectomy (removal of parathyroid glands) – in the presence of primary hyperparathyroidism/parathyroid hyperfunction (elevated serum calcium; laboratory diagnosis: determination of intact parathyroid hormone).