Prevention of Kidney Stones

Some sort of follow up is likely to be recommended regardless of how your stone presented or was treated. Patients with acute ureteric colic will usually be seen to make sure that the stone has passed; patients with an incidental / asymptomatic stone will be seen for review with imaging to make sure it does not enlarge, and patients who have had active intervention will be seen to ensure their recovery has been as expected, and with imaging to confirm clearance of the stone, or to identify residual fragments that might require further treatment or simply to be monitored. Determining what follow up, with what imaging and when is clearly an individual patient discussion with their urologist based on their particular circumstances, so will not be elaborated on further here. However, all patients, regardless of initial stone burden or treatment are likely to have a discussion about preventative strategies for reducing the risk of recurrent stone formation.

General measures to Prevent Recurrent Episodes

You will normally be given specific advice about changes to your diet and fluid intake which will reduce the risk of further stone formation.

Overwhelmingly the most important measure is to increase your daily fluid consumption, including of water, to achieve a daily urine output of between two to two and a half litres of urine. As it sounds, this is quite a lot of fluid, but is made more manageable by drinking little and often continuously during the day, rather than going from periods of dehydration to drinking lots in one go. There is no need to use expensive bottled water – tap water is absolutely fine.

There is some evidence that stone inhibitor levels (especially citrate) can be increased by drinking fresh lemon juice in water. This is useful for uric acid stones (as the citrate helps to make the urine more alkaline, in which uric acid is more soluble, so less likely to form a stone) and calcium oxalate stones (as citrate is an inhibitor of calcium-oxalate precipitation).

Contrary to what you might have been told or thought intuitively, you should NOT restrict your calcium intake, even if your stone is made out of calcium. Indeed, large studies have shown that a normal calcium intake (i.e. following a healthy, varied diet) is PROTECTIVE against future stone formation, and attempting to have a low calcium diet (which is quite challenging as Calcium is present not only in milk, cheese and other dairy products but also in animal protein) INCREASES the risk of stone formation.

Other general advice includes a reduction in the amount of animal protein in the diet, and a reduction in the amount of salt and sugar in the diet. The latter cause the kidney to excrete more calcium, and thereby increase the risk of stone formation.

Specific Medical treatment for High-Risk Stone Formers

Patients who are deemed particularly high risk, either through their personal or family history of stones, or having a large volume of stone at presentation (especially if both kidneys are affected, or they have only one kidney for one reason or another) may be offered additional medical treatment to reduce their risk of future stones. This advice will usually be guided by the stone biochemistry and a 24-hour urine collection (see above).

Specific medical treatments include:

Urinary alkalinisation with potassium citrate or sodium bicarbonate for Uric acid stones

Thiazide diuretics to reduce the calcium level in the urine.

Tiopronin or d-penicillamine to help reduce the risk of cystine stone formation in those confirmed to have cystinuria.

These treatments may be advised by your Urologist for your GP to continue; alternatively, additional expertise from other clinicians with an interest in stone disease and its prevention may be sought on your behalf. This may involve your being referred to a Nephrologist (renal physician) or other medical doctor interested in kidney stone formation (such as an endocrinologist or biochemist).

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