Kidney Stone Prevention Strategies
Kidney stones are painful. Walking through an Emergency Department, it is often quite evident who is there trying to pass a stone. As the stone passes from the kidney down the ureter and into the bladder, patients feel strong, intense pain in the flank, sometimes radiating to the front and down to the groin. Kidney stone pain is often compared to a woman’s pain while in labor. Symptoms of kidney stones may also include increased urinary urgency and frequency, blood in the urine, and often, nausea and vomiting.
Kidney Stones affect one in every eleven Americans
Kidney stones are quite common, affecting one in every eleven Americans. To make matters worse, up to 50% will have another stone within 10 years. After patients have gotten through the first stone episode, whether that is by passing the stone or by having to undergo a surgical procedure to remove the stone, the next question is always, “How can I make sure that this never happens again?”
The first choice for stone treatment is for the patient to be able to pass the stone on their own. When that is unsuccessful, we consider surgical treatments including ureteroscopy and extracorporeal shock wave lithotripsy (ESWL).
During an ureteroscopy procedure a small ‘telescope’ goes into the bladder and up the ureter to where the stone is located. If the stone is small, it is snared with a basket device and removed whole from the ureter. If the stone is large, or if the diameter of the ureter is narrow, the stone will need to be fragmented, which is usually done with a laser. Once the stone is broken into tiny fragments, they are removed.
The other surgery is ESWL, where sound waves are passed from outside of the body aimed at the stone. The power of these sound waves breaks the stone into fragments small enough to pass through the ureters.
While it is not possible to prevent every patient from ever making another stone, there are strategies patients can follow to reduce their future risk. These important steps include increasing fluid intake and making dietary changes. However, it is not a one size fits all strategy, and that is why it is important to follow up with a Urologist for an evaluation.
Increase fluid intake and make dietary changes
In the first visit with the Urologist a detailed medical and dietary history should be obtained. If the patient is able to catch the stone, it is important to send it to a lab to determine the stone type, as that will help guide prevention and dietary recommendations.
Urine and blood tests should also be obtained to provide additional clues as to why the stone formed. If this is not the first stone, or there is a strong family history of stones, then a 24-hour urine collection should be done to evaluate the urine chemistries. The results will allow us to determine if the patient has too much or too little of certain compounds which may increase the risk of stones.
If your urine is dark yellow, you need to increase fluids
The most important recommendation is to drink more water. Every stone former should drink enough water to produce at least 2.5 liters (83 ounces) per day of urine. It has been shown that for every 200 mL (6.7 ounces) consumed the risk of stone disease goes down by 13%. If you are not the type of person that wants to measure your urine output, a simple rule of thumb is that if your urine is clear to very pale yellow, you are drinking enough. If it is dark yellow, you need to increase fluids.
Reduce the salt in your diet
While it is true that most kidney stones contain calcium, it is rare that the problem is the intake of calcium in your diet. Avoiding milk and cheese is not the right answer. In fact, it is more important to reduce the salt in your diet as opposed to calcium. Guidelines by the American Urological Association recommend a low sodium diet of 2000-3000 mg and a moderate calcium intake of 1000-1200 mg daily.
If you do eat a lot of oxalate rich foods, add cheese
Most stones are made of calcium oxalate, and it is often more important to control the amount of oxalate in your diet. Your physician can supply you with a list of oxalate rich foods but some examples are leafy vegetables, tea, chocolate and nuts. If you do eat a lot of oxalate rich foods, add cheese. The oxalate and the calcium will then bind within your intestines and not get absorbed to a high degree, so those stone-producing molecules stay out of the kidney.
A diet rich in fruits and vegetables adds citrate, helps prevent stone formation
The compound citrate is found in urine and helps prevent stone formation. A diet rich in fruits and vegetables can add considerable citrate to the urine chemistry and help prevent the calcium and oxalate molecules from binding. A common recommendation with the increased water intake is to add fresh lemon to the water so that you are also increasing your citrate intake as you drink.
Reduce the intake of animal protein
A final dietary recommendation is to reduce the intake of animal protein. Uric acid stones are quite prevalent and uric acid found in meat is a key contributor. Patients with gout certainly understand the issues with a high level of uric acid and the risk for stone formation. A good rule of thumb is to make at least one meal a day vegetarian, this can reduce the dietary uric acid considerably.
Make at least one meal a day vegetarian
The most important dietary modification to prevent the formation of kidney stones is to drink more water. Become the person that carries around a water bottle. Eat a balanced diet with lots of fruit and vegetables to increase your citrate levels. Reduce your consumption of animal protein. Don’t avoid dairy or other calcium containing foods because calcium is important to have in your system to maintain bone health.
No one wants to have kidney stones and anyone who has had one in the past certainly wants to avoid another one. By following these recommendations, and seeing a Urologist, when appropriate, we hope to keep you from those visits to the Emergency Department.
Stephen B. Siegel, MD
Boulder Medical Center
2750 Broadway Street
Boulder, CO 80304
Phone: (303) 440-3093
Fax: (303) 440-3161