What are kidney stones?

The kidneys are two bean-shaped organs on either side of the spine, just below the rib cage. They are essential for filtering blood, regulating fluid balance, controlling blood pressure, producing urine and red blood cells, activating vitamin D, and maintaining the body’s pH balance. When the kidneys can’t remove all waste from the urine, hard, pebble-like deposits of minerals, known as kidney stones, can form. Baylor Medicine urologist Dr. Justin Badal  explains what kidney stones are, in addition to how to effectively treat and prevent this condition.

“Each year, more than half a million people visit emergency rooms for kidney stone complications,” said Badal, assistant professor in the Scott Department of Urology. “While kidney stones are more prevalent in men than in women, they can develop at any age. The size of kidney stones varies; some are as small as a grain of sand, while others can be as large as a golf ball.”

Stones are made when urine is too concentrated with electrolytes forming into small crystals, typically due to a lack of proper hydration. When these crystals join with other elements, a solid is created. There are different types of kidney stones:

• Calcium oxalate: This is the most common type of kidney stone and is created when calcium combines with oxalate in urine.
• Uric acid: This is another common type of kidney stone. Meat and shellfish have high concentrations of a natural compound called purines, which can lead to a higher volume of uric acid in the urine. Under the right conditions, uric acid can form stones in the kidneys.
• Struvite: Less common and caused by infections in the upper urinary tract.
• Cystine: These are rare and tend to run in families.

The symptoms and their severity are determined by the size and location of the kidney stone. Symptoms can include:

• Severe, stabbing pain on either side of the lower back.
• Pain that radiates from the back down to the groin.
• Blood in urine.
• Nausea or vomiting.
• Fever and chills.

As with any other condition, the diagnosis of kidney stones begins with a medical history, physical examination, laboratory work and imaging tests. Your provider will want to know the size and location of the kidney stone and will typically order a CT scan. You also will be evaluated using blood and urine tests to assess for the severity of the blockage and presence of infection. Once the stone passes or is removed, the cause of the stone can be determined. But remember to strain your urine to catch the stone and bring it in for analysis.

In many cases, the stones pass by themselves without surgical intervention, but in some cases, more intensive treatment is needed. Treatment options can range from:

• Shock-wave lithotripsy: a non-invasive procedure that uses high-energy sound waves to break the stone into fragments that are more easily passable in the urine. (About a 70% likelihood of repeat stone events 8 weeks after surgery).
• Ureteroscopy: a small camera is inserted through urethra and into the bladder and then the ureter to retrieve or break up the stone using laser energy. (About a 50% likelihood of repeat stone events 8 weeks after surgery).
• Percutaneous nephrolithotomy/nephrolithotripsy: a minimally invasive surgical technique where instruments are inserted through the back and into the kidney directly to remove or break down the kidney stone. (About a 30% likelihood of repeat stone events 8 weeks after surgery).

The decision for surgery is one made carefully by a urologist and warrants a discussion with your physician. Stone size and location play an important role in deciding which option is best.

“The best way to prevent kidney stones is by drinking a lot of water. This has the highest impact on stone prevention. Repeat stone formers are advised to drink enough water to produce 2-2.5 liters of urine per day. That can be about 3-4 liters of water per day,” Badal said.

A diet high in fruits and vegetables also helps make the urine less acidic. Reducing the amount of salt in your diet also is important to prevent kidney stones as it directly reduces the amount of calcium in the urine. Avoiding calcium is not necessary and can be important to help prevent stones from forming. It is best to speak to your doctor or a registered dietitian about making changes to your diet if you are at risk for forming kidney stones.

By Alexandria Brown, senior marketing associate in the Scott Department of Urology