You might remember the scene in the ’90s sitcom Friends where Joey is lying in a hospital bed struggling to pass a kidney stone while Phoebe, in a separate room at the very same time, is giving birth to triplets. As the story switches between the two rooms, the two friends’ cries and yowls of pain are matched.

Although it’s a funny scene, the excruciating pain that accompanies kidney stones is not a laughing matter. Kidney stone pain lands more than half a million people in emergency rooms each year, the National Kidney Foundation reports, and incidences of kidney stones have been continually increasing, even in kids.

While there may be many factors to blame for this, there’s one that researchers agree on: diet. A diet high in animal protein can increase your risk of developing kidney stones, the American Urologic Association states, and several studies back this up.

The Recommended Dietary Allowance for protein is a 0.36 grams per pound of body weight. In a balanced diet, protein should account for between 10% and 35% of all calories consumed. For an adult who weighs 150 pounds, that's about 54 grams of protein a day. High-protein diets commonly include around 75 grams of protein a day, or even as much as more than 100 grams.

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Dr. Phillip Marks

Wondering what else might increase your risk of the dreaded stones, and what the heck kidney stones are made of to begin with? Here to answer your questions is Dr. Phillip Marks, a urologist at Novant Health Urology - Wilmington.

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What exactly are kidney stones?

Kidney stones are hard deposits that can form in your kidneys, two bean-shaped organs in your upper abdomen, each about the size of your fist, that make up part of the upper urinary tract. Your kidneys are responsible for filtering waste products and excess water from the bloodstream to form urine. Kidney stones are made from different minerals and salts.

The four types of kidney stones are:

  1. Calcium stones, 80% of stones. Calcium stones may be made of calcium oxalate or calcium phosphate, with calcium accounting for a large majority.
  2. Uric acid stones, 5% to 10% of stones. Uric acid is a waste product that comes from chemical changes in the body. Uric acid crystals do not dissolve well in acidic urine and instead will form a uric acid stone.
  3. Struvite stones, 10% of stones. These are related to chronic urinary tract infections (UTIs). Some bacteria make the urine less acidic, which allows these stones to grow.
  4. Cystine stones, less than 1% of stones. Cystinuria (too much cystine in the urine) is a rare, inherited metabolic disorder. The kidneys do not reabsorb cystine from the urine in people who have this. When high amounts of cystine are in the urine, it causes stones to form.

Is it important to know what type of stone I have?

Marks explained that knowing the composition of the stone is important for managing treatment and prevention. “However,” he continued, “this does not necessarily tell you how you made it.”

So successful kidney stone treatment and prevention isn’t just about determining a stone’s composition; it also involves diving into a person’s medical and lifestyle history to examine what is causing the formation of the stone.

“There's usually some sort of metabolic inborn error, along with other medical problems, and lifestyles that will contribute to the formation of stone disease,” Marks said. “So getting to the root cause is important.”

And that’s where Marks and other Novant Health urologists come in. They can run tests to help determine the root cause of the stone formation, which is important to ensure one kidney stone doesn’t become many over time.

“We’ll come up with a treatment plan that will manage that and help prevent future stone episodes. That's the goal,” Marks said.

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