The Facts About Kidney Stones

Understanding Why They Happen and How to Avoid Them

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Kidney stones are solid, pebble-like masses that develop in the urinary tract from salt and minerals that have clumped together in the urine. The process, called urolithiasis, can result in either a small stone that is easily passed during urination or a larger stone that can block a ureter (one of two tubes which propel urine from the kidney).

Symptoms

When a blockage occurs, a person can experience often excruciating pain radiating from the back and sides to the pelvis, groin, and genital areas.

Other symptoms include:

  • the feeling that you need to urinate constantly (urinary urgency)
  • intense burning when you try to urinate
  • fever and chills
  • blood in your urine
  • nausea and vomiting
  • cloudy urine or urine that smells bad
  • loss of appetite
  • sweating 
  • restlessness

Risk Factors

Most kidney stones form as a result of both genetic and environmental factors. Men are more prone to kidney stones than women as are people between the ages of 30 and 60.

Other risk factors include:

  • high urine calcium levels
  • dehydration/not drinking enough fluids
  • a family history of kidney stones
  • obesity
  • diets high in animal proteins
  • low dietary magnesium
  • high sodium intake
  • drinking fluoridated water
  • taking excessive calcium, vitamin C, or vitamin D supplements
  • excessive parathyroid activity
  • gout

Kidney stones are also more common in the southern United States, where the persistent, dry heat and dietary factors contribute to their development.

As a result, the area is often deemed the "Kidney Stone Belt."

Types

There are several types of kidney stones, each of which is linked to various biological, environmental, genetic, and dietary causes:

  • Calcium stones are the most common type. They are seen commonly in post-menopausal women who take excessive calcium and vitamin D supplements (greater than 1000 mg. and 400 IUs, respectively).
  • Uric acid stones occur in people with a high urine acidity (as can happen with gout).
  • Struvite stones tend to develop as a result of infection. 
  • Cystine stones are rare and tend to run in families.

Diagnosis

Imaging tests, including X-ray, ultrasound, and computed tomography (CT scan), can be used to pinpoint the size and exact location of the stone. These tests are extremely helpful in determining whether the stone will pass naturally or require more aggressive treatment.

Treatments

There are several schools of thought regarding the treatment of kidney stones. Oftentimes, decisions are based on the size and location of the stone. Specialist training and experience will also direct which course of action a urologist will likely take.

Conservative treatment is most often indicated in people with smaller stones. The doctor will advise you to drink a lot of water while providing you painkillers to help tolerate the pain. You may also be asked to have a strainer on hand to catch the stone when it passes so that it can be analyzed in the lab. This can help determine which foods or factors led to the stone's formation.

For larger stones, a more aggressive approach may be needed, including:

  • Extracorporeal shock wave lithotripsy (ESWL) is a technique that uses a specialized machine to break up a stone from outside of your body, allowing you to pass the stone more easily.
  • Percutaneous nephrolithotomy (PCNL) involves inserting a tube through a small incision to help drain the kidney.
  • A ureteroscope (a small, tube-like instrument equipped with a camera) can be inserted into the urethra (the opening through which urine is expelled from the body) to either manually extract the stone or break it into tiny pieces.

Prevention

There are several ways to prevent kidney stones if you've had them in the past or are at risk of developing them:

  • Drink more water to continually flush out the urinary tract.
  • Avoid drinking more than one to two cups of caffeinated beverage per day.
  • Restrict your intake of cola or any drink that contains phosphoric acid.
  • Eat less animal protein and refined sugars.
  • Increase your natural intake of citric acid, particularly from lemon or lime juice.
  • Avoid foods containing high fructose corn syrup.
  • Avoid excessive vitamin C supplementation.
  • For oxalate stones, restrict your intake of concentrated citrus juice, chocolate, beer, tea, or dark green vegetables.
  • For calcium stones, restricting your salt intake
  • For uric acid stones, reduce your intake of meat, fish, and poultry.
  • Avoid excessive calcium and vitamin D supplementation if you are post-menopausal.

Your doctor may also prescribe a diuretic, cellulose phosphate, or potassium citrate to facilitate calcium excretion if you have had calcium stones.

Sources

  • National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health. "Kidney Stones." Bethesda, Maryland; updated September 2016.

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