How can kidney stones be prevented?

Unfortunately kidney stones are a recurrent disease, meaning that if you have one stone you are at risk for another stone event. In general, the lifetime recurrence risk for a stone former is thought to approach 50%. Stone prevention, therefore, is essential. Your doctor or urologist may follow up with several tests to determine which factors e.g., medication or diet should be changed to reduce your recurrence risk.
A good first step for prevention is to drink more liquids and water is the best. If you tend to form stones, you should try to drink enough liquids throughout the day to produce at least two liters of urine in every 24-hour period. People who form calcium stones used to be told to avoid dairy products and other foods with high calcium content. However, recent studies have shown that restricting calcium may actually increase stone risk.  High doses of calcium, Vitamin D, or Vitamin C may increase the risk of developing stones, especially in people with a family history of stones. These people need to be careful and should calcium supplementation be needed, calcium citrate is best.
If you are at risk for developing stones, your doctor may perform certain blood and urine tests to determine which factors can best be altered to reduce the risk. Some people can decrease their risk with dietary changes while others will need medicines to prevent stones from forming.
Other general recommendations for stone formers is that they consume a low sodium and low animal protein diet.
Do not be surprised, if you are asked to collect urine for 24 hours after a stone has passed or been removed to measure volume and levels of acidity, calcium, sodium, uric acid, oxalate, citrate and creatinine. This information will be used to determine the cause of the stone. A follow-up 24-hour analysis may be used to find out the effectiveness of treatment.