Severe pain, waves of nausea, and blood in the urine. As anyone who has had to pass a kidney stone will tell you, the experience is rarely described as a pleasant one.
Emergency rooms in the U.S. see more than 500,000 patients every year for kidney stones, according to the National Kidney Foundation. And, if you have already had one kidney stone, the foundation reports there is a 1-in-2 chance you will get another one.
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A new study coordinated by the Duke Clinical Research Institute investigated why recurrence rates are so high, despite hydration being a seemingly simple and effective prevention method.
Dr. Charles Scales, co-senior author of the study published Thursday, said the research found that producing 2.5 liters of urine daily can help prevent kidney stones by diluting the urine. However, many patients struggle to drink enough fluids to reach that target.
“A kidney stone, in layman's terms, is a mineral that has crystallized in the urine. The minerals are usually dissolved in the urine, but if there are enough minerals in the urine, then they turn into a crystal,” Scales explained. “If the urine is more dilute, it is much harder for those minerals to crystallize and turn into a kidney stone.”
The trial is the largest behavioral study for kidney stone prevention. Researchers enrolled 1,658 adolescents and adults at six U.S. clinical centers, and followed them for two years.
“Kids get kidney stones too, and not many people know that, but it's something that definitely happens,” Scales said. “They’re doubling in prevalence, just like the rest of the population in the United States.”
Participants in the study had at least one previous kidney stone along with low urine output. Two-thirds of the participants had multiple kidney stones before enrolling in the trial.
“What we wanted to know was not just could we get people to drink more fluid for 2-8 months, but for a long time, in which they might actually prevent kidney stone formation. It takes about two years to form a kidney stone,” Scales said.
The control group in the study received the standard of care, which includes instructions to drink more fluids. Other participants were given specialized water bottles, equipped with Bluetooth that measured fluid intake and output, personalized hydration goals, and other incentives such as reminder texts.
The results found that people in the behavioral program did hydrate more than the control group, but did not drink enough to lower their chances of developing another kidney stone.
The findings highlight a key challenge: even when people know hydration can help prevent kidney stones, consistently drinking enough fluids every day is difficult.
Scales said the findings point to the need for more personalized treatment plans to help patients meet necessary hydration goals while navigating busy lifestyles rather than a one-size-fits-all approach.
“If we think about a rideshare driver, how do you make sure you have enough water? How do you make sure you can find a bathroom when it's convenient? It's really hard for some people, depending on their occupation, to be able to drink fluid,” Scales mentioned. “Just drinking enough fluid is really challenging.”
While drinking fluids remains one of the most effective ways to reduce risk, Scales encourages patients to work with a specialist to find a plan that fits their lifestyle.