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Are You at Risk for Kidney Stones? Doctors Reveal the No. 1 Condition That Ups Your Odds

Plus, find out why living in America's 'stone belt' makes you more prone to the painful condition

Every year, over half a million Americans land in emergency rooms seeking relief from kidney stones. And the likelihood of having this painful condition has increased significantly, from nearly 4% in the late 1970s to 10% today. As more people deal with these crystal formations in their urinary tract, it’s important to understand what causes them. We asked experts to share the biggest risk factors for kidney stones that everyone should know.

The 4 types of kidney stones

“Stone disease is not just one disease,” says John Rodman, MD, a New York City-based urologist and lead author of No More Kidney Stones. “There are different types, each with different causes with treatments based on the stone’s composition.”

Calcium-based stones account for about 80% of cases. The second most prevalent are uric acid stones, which form when urine is too acidic. Struvite stones are linked to urinary tract infections. And cystine stones, the rarest type, result from a genetic disorder known as cystinuria.

Historically, men got more calcium stones than women. But the gender gap is closing. “It used to be more common to see women for struvite stones related to infection,” Dr. Rodman says. “But today, it’s more equal opportunity — likely because women are engaging in similar activities and have comparable diets to men.”

An illustration of kidneys with kidney stones

How age affects your risk of kidney stones

Stones can strike at any age. “I just saw a patient today who is 88 and this is her first kidney stone,” says urologist Timothy D. Averch, MD, FACS, Chief of the Division of Urology with Prisma Health-Midlands in Columbia, South Carolina. “It can happen at any age, even in childhood. Calcium oxalate stones, the most common ones, typically strike younger, with people in their 20s through 40s most prone. It typically becomes less of an issue by middle age,” adds Dr. Averch.

But as we age, uric acid stones become more common. That’s often due to high-protein or salty foods and metabolic issues often associated with being overweight, Dr. Rodman explains. For women, weight gain after menopause can alter how the body processes sugars and fats, leading to metabolic conditions that favor stone formation, he adds.

Dehydration is a top risk factor for kidney stones

“It’s a fact that if you’re dehydrated, you are more likely to make a stone because your urine is more concentrated,” Dr. Rodman says. Indeed, increased minerals and salts in your urine are more likely to interact and form stones without enough fluid to dilute them. That’s why maintaining adequate hydration is crucial not only for preventing stones, but also for aiding their passage. “We want stone formers to make two liters of urine a day,” adds Dr. Rodman.

Surprisingly, your home town also plays a role in your risk of kidney stones. The “stone belt” — a swath of Southeastern states like North Carolina and Virginia — has a higher incidence of kidney stones due to their hot, humid climates. This leads to increased sweating, reduced fluid intake and more concentrated urine for people living in those areas. (See how an emotional support water bottle can help you increase your fluid intake.)

More risk factors for kidney stones

Certain health conditions can also make it more likely that stones will form. That includes gout, Crohn’s and other inflammatory bowel disorders. What else is at play?

1. Your diet

The modern American diet, high in processed foods, salt, sugar and meat, is another one of the biggest risk factors for kidney stones. “Animal protein breaks down into uric acid, which is a factor we know contributes to kidney stones,” Dr. Averch says. “Something we don’t fully understand is how it also generates extra calcium in the urine, and this doesn’t happen for everyone.”

A table full of processed foods, such as pizza, burgers, fries, onion rings and soda, which are risk factors for kidney stones
Anastasiia Krivenok/Getty

Moreover, high fructose intake, commonly from sugary beverages and snacks, is also linked to stone formation. Some leafy greens and foods generally considered healthy, like spinach, also are a problem to some because of their high oxalate content. Oxalates are a natural chemical that binds with minerals in the urine to form stones. High oxalate foods include tomato sauce, peanut butter, bok choy, rhubarb, beets, nuts and tea. (Learn more about oxalates and how they affect your health.)

2. Genetics

“All those foods [above] that would normally be good for a diet are bad for kidney stones if you’re a stone former,” Dr. Rodman says. “Spinach is the worst food you can eat. It’s the highest oxalate containing food.”

“If two people are eating the same diet with too much salt or too much meat, it’s hard to say if either of them will get kidney stones, even though those are risk factors,” he adds. “One hundred people could all be doing the same things — in terms of eating and exercise habits — and only a few will form stones.”

However, if kidney stones run in your family, your chances of forming them increases substantially. That said, there are no known specific genetic markers to predict who will get them, adds Dr. Averch.

3. Your vitamin C intake

While it’s thought that high doses of vitamin C help ward off infections, Dr. Rodman says this is a “common misconception” and can actually lead to kidney stone formation. It’s true that moderate vitamin C use benefits our immune system. But large amounts are unnecessary and can increase the production of oxalates.

“Nobody makes stones because they take 250 mg of vitamin C,” he adds. “I’ve helped lots of people stop making stones when I got them off the 2 grams of vitamin C.” As for how much C is safe, Dr. Rodman says, “all we can say is that 250 mg seems to be a level that does not raise oxalate content much.” Talk to your doctor about what dosage is right for you based on your specific medical history.

For more ways to keep your kidneys healthy:

Home Remedies for Kidney Stones: Natural Ways to Ease Pain + Prevent Future Issues

MD Reveals the Kitchen Staple That Outsmarts Painful Kidney Stones For Pennies

If You Notice Your Nails Turn This Color, It Could Be an Early Warning Sign of Kidney Disease

This content is not a substitute for professional medical advice or diagnosis. Always consult your physician before pursuing any treatment plan.

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