When a first kidney stone has passed, many patients are simply advised to drink more. However, a quarter of adults will have a new calculation within five years, and half will relapse if they have already had several episodes. A large review of the medical literature shows that other levers, dietary and medicinal, can also help limit this risk.
Published in Annals of Internal Medicinethis systematic review brought together 31 studies, including 26 randomized trials, in adults and some children who had already presented with stones. The authors assessed the impact of a adapted dietseveral medications and possible surveillance imaging to prevent recurrence of kidney stones. And certain results challenge preconceived ideas.
Why kidney stones recur so often in adults
The most common kidney stones in adults are composed of calcium oxalate or phosphate. They form when urine is too concentrated, too acidic or too rich in certain minerals, often with a fluid intake
insufficient. Once a first calculation appears, the ground remains fragile: without a prevention strategy, the risk of a new episode reaches around 25% at five years.
The review also shows that, for these calcium stones, there is a lack of data on the benefit of increasing the number of scans or ultrasounds to avoid recurrence. The researchers therefore focused on modifiable factors: what happens when we really increase the water we drink, adjust the salt and animal proteins, and then add certain medications targeting urinary calcium or uric acid?
Diet: changes that help prevent recurrence
An old Italian trial, included in the journal, shows that simple advice, aiming for at least two liters of urine per day, reduces recurrences by around 148 cases per 1,000 patients over five years, compared to no special recommendation. In practice, this often means drinking more than 2 liters of water per day, splitting the intake and adapting according to heat or physical activity.
Another interesting result, a diet with normal to high calcium intake but low in salt and animal proteins was more protective than a diet low in calcium in men with hypercalciuria. The review estimates 183 recurrences avoided per 1,000 patients. French recommendations therefore aim for 800 to 1,200 mg of dietary calcium per day, around 4 to 5 g of salt and nearly 1 g of animal protein per kilo of body weight.
Medications: thiazides, citrates, allopurinol, for which patients?
On the medication side, three families stand out for calcium stones: thiazide diureticsTHE
alkalizing treatment with citrate and theallopurinol. Overall, studies suggest approximately 200 fewer recurrences per 1,000 patients treated with thiazides, 300 fewer with citrates, and 260 fewer with allopurinol, with few serious adverse effects reported. These treatments remain reserved for adults, after metabolic assessment, because the data remain very limited in children.
Finally, no research has examined the use of imaging as a preventative method. In general, the analysis indicates that although various strategies may provide modest benefit, additional studies are required to validate the effectiveness of certain interventions and clarify possible risks.