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Kidney Stones

BACKGROUND

Kidney stone disease has been described since antiquity and has become a widespread problem in modern western culture and our society. The lifetime prevalence of kidney stones in north America is estimated between 7-13% depending on geographic location, age, race, and other medical factors. On average it is estimated that 1 in 10 adults in the US suffer from kidney stones. Kidney stones are also more common among Caucasians with near equal distribution between men and women. The incidence peaks between ages 40-60 years old. 

What causes kidney stones?

As one of the common contributors to kidney stone formation is dehydration, the prevalence of this disease is higher in hot and dry climates such as the southeast of the United States. Also, because sunlight induces an increases in natural vitamin D, calcium absorption increases, thereby leading to increased calcium in the urine. This increase in calcium along with the relative dehydration that often occurs in the summer months, may then lead to the perfect set up for kidney stone formation. 

Certain occupations such as cooks or steelworkers who are exposed to high temperatures at work and are not able to replenish their fluid losses are at higher risk of kidney stones. Obesity and dietary factors are also strong contributors to kidney stones. Diseases such as high blood pressure have also been linked to kidney stones as those individuals tend to have more sedentary life styles or consumes increased amounts of foods or salts that are associated with kidney stones. 

Certain disease states that increase urinary calcium levels such as hyperparathyroidism can also increase a person's risk of recurrent kidney stone formation. It is important to visit an experienced urologist in kidney stone management to determine if there are any risks factors or disease states that put you at risk. 

What symptoms do kidney stones cause? 

Most kidney stones that are in the kidney are asymptomatic. However, once a kidney stone starts to mobilize and gets fully or partially stuck in the ureter, the tube that empties the kidney, then symptoms occur. These consist of a sharp and sometimes crampy pain in the flank or back area with radiation to the abdomen and sometimes pelvis and groin. The symptoms may come about suddenly and wax and wane. Urinary frequency and urgency may be experienced as the stone gets closer to the bladder. A burning sensation with urination is possible, especially if there is accompanying infection. Most people also experience nausea and vomiting which may lead to significant dehydration. 

How are kidney stones diagnosed? 

A noncontrast CT scan is the gold standard in diagnosing kidney stones with a sensitivity of 98% and specificity of 97%.  Plain x-rays also called KUB have a sensitivity of 57% and specificity of 76%. Ultrasound of the kidney in comparison has a sensitivity of 61% and specificity of 97%. The added benefits of ultrasound are that it does not contain radiation, is often available in the physician office, and is relatively cost effective. 

How can you prevent kidney stones? 

As discussed earlier, dehydration and low urine volume are the most important risk factors for kidney stone formation. Increased fluid intake to achieve a urine output of at least 2.5L/day (85 oz) is recommended by both the American Urological Association as well as the European Urology Association. 

Carbonated beverages such as Coke which contain phosphoric acid and fructose have been shown to increase the risk of kidney stones. Certain diuretics such as black coffee and wine are associated with lower rates of kidney stones. 

Since the most common kidney stone in the US is calcium oxalate, taking in a low oxalate diet may be beneficial. Majority of plants have oxalate but foods such as spinach, almonds, beets, and rhubarb tend to have a higher oxalate content. You can search for lists of oxalate containing foods online or ask your urologist or nutritionist for recommendations. 

Animal protein (meat, fish, poultry) has also shown to increase the risk of calcium oxalate stones. Fruits and vegetables have shown to reduce risk of stone formation and are encouraged in frequent stone formers. 

Reduction of daily salt intake is also important in kidney stone formers. It is recommended to reduce salt intake to 100mEq or 2300mg per day while increasing fluid intake as mentioned above. 

In Summary:

  • Drink at least 2.5-3L of water per day

  • Reduce carbonated beverages such as Coke and Pepsi 

  • Eat plenty of fruits and vegetables 

  • Reduce your daily salt intake 

  • Reduce your animal protein intake 

  • Eat foods with low oxalate levels 

  • Take in a normal daily recommended amount of calcium 

How are kidney stones treated? 

Once kidney stones are diagnosed, their treatment will depend on size and location as well as symptoms. It is important to see a urologist to discuss which treatment is appropriate for your individual case.

 

If a kidney stone is relatively small with high chance of passing itself, then certain medication may help with the process and avoid surgical intervention. These medications are often prescribed by an emergency room physician or your urologist. 

 

In general if a stone meets criteria, Extracorporeal Shockwave Lithotripsy (ESWL) or more commonly referred to as "litho", is the least invasive modality with the least number of potential complications.

 

Advanced endoscopy has allowed urologist to use small cameras to obtain access to the entire urinary system and treat various ailments such as kidney stones. This is also considered very safe and effective but is more intrusive and invasive than ESWL

Large kidney stones may be treated through slightly more invasive techniques such as Percutaneous Nephrolithotomy (PCNL) by gaining access to the kidney through the back. This technique is best for larger stones and may allow more complete clearance of stones in one setting. However, this is also more invasive and requires more advanced surgical skills. Some urologist do not provide this service and therefore it is important to seek a urologist who is well versed in this technique. 

Depending on the size and anatomic considerations laparoscopic or robotic kidney stone surgery may be the best option. These are advanced treatments and require specialized training. They are also more invasive than the techniques discussed above and carry higher risk of complications. However, in experienced hands, these procedures could save a kidney! 

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As always, the information above is meant to be informative and does not replace your physician's recommendations or judgement. Each individual case has to be evaluated carefully to determine the best course of action. Call or use our contact page to request an appointment to further discuss your unique case.

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