A dearth of kidney stone specialists is colliding with a rise in the number of patients who need specialized care.
While increasing the number of nephrologists who specialize in kidney stones is necessary, nonspecialists need to play a larger role in recognizing and preventing kidney stones.
Primary care and emergency room physicians can be the front lines of counseling patients who do not have underlying genetic causes of kidney stones on how to prevent a recurrence, according to Irina Jaeger, MD, a urologist at University Hospitals and an assistant professor of urology at Case Western Reserve University School of Medicine, both in Cleveland, Ohio.
"A lot of this care can be implemented by our primary care physicians, such as counseling on decreasing sodium in the diet and increasing fluid intake, which benefits so many different health conditions as well as stones," said Gregory E. Tasian, MD, MSCE, an attending pediatric urologist at Children's Hospital of Philadelphia, Pennsylvania. "If we can think about this holistically, we can really make strides."
Focus on Prevention
Taking a holistic approach, Tasian added, will require rethinking how health teams approach patient care and manage kidney stones.
"We think of stones as episodic events that are painful, and then pass," he said. "But it's really a disorder of mineral metabolism."
Understanding these episodes as a chronic disease can also explain why nephrolithiasis often goes hand in hand with higher instances of heart attack and stroke, hypertension , and bone breaks, he added.
Simple measures like staying hydrated and consuming citrate in the form of lemon water or lemonade can help patients prevent recurring kidney stones, Jaeger said.
But patients who have had a stone also need to see a specialist to rule out any underlying causes. Kidney stones are routinely viewed as episodic events that don't pose much of a health threat, but between 30% and 50% of people diagnosed with stones will experience a recurrence within 5 years. Educating patients on how they can prevent future episodes is a crucial part of care.
"Even if they are passing the stones on their own without surgery, they should really be evaluated by a urologist or a nephrologist," Jaeger said.
David Goldfarb, MD, clinical director of the Division of Nephrology at NYU Langone Health, in New York City, said that access to nephrologists who specialize in kidney stones is a critical piece of prevention. While urologists can treat stones, nephrologists get to the bottom of why the stones occurred in the first place and help patients prevent further stones from forming.
"The majority of urologists in the U.S. don't do much in regard to prevention," he said. "There needs to be more nephrologists."
Kidney stones now appear to be increasingly common in patient populations that previously did not have the condition.
A study published in 2016 in the Clinical Journal of the American Society of Nephrology found that the annual incidence of kidney stones increased 16% from 1997 to 2012, with the biggest increase seen among teenagers. Stones were 52% more common among girls and women than among men, but the condition is also becoming more common in men starting at age 25. Meanwhile, Black Americans of all ages saw greater rates of kidney stone development than their White counterparts.
Fewer residents are also choosing to specialize in nephrology, with a decrease in the choice of fellowship of 50% from 2009 to 2019, according to a 2023 report by the American Society of Nephrology.
A 2019 survey of nearly 4200 residents found that only 60% of nephrology fellowship positions were filled in 2018, and the majority of those residents reported a lack of interest in the kidney as being the most critical factor in not selecting the specialty. Others reported lack of exposure to nephrology overall.
Diagnosing the Root Cause
Getting to the root cause of how further kidney stones can be prevented usually requires a nephrologist, according to Jaeger.
"As a urologist, 90% of what we do is surgery," Jaeger said.
Although urologists are trained in analyzing 24-hour urine tests, which can reveal risks that can be addressed by preventive changes, many urologists tap a specialized nephrologist, who may analyze the samples with a keener eye.
"When individuals pass a stone, fewer than 10% seek care with a specialist after that and that's a missed opportunity to prevent future stones," Tasian said.
Not all nephrologists specialize in stones, but they may be better equipped to recognize when a patient needs to see someone who does. Failing to involve a nephrologist who specializes in kidney stones can have grave consequences for patient health.
Goldfarb is currently caring for a patient with a kidney transplant that had begun to lose function. Clinicians who originally cared for the patient took a kidney biopsy, which showed fragments of calcium oxalate, a common type of kidney stone, in her native kidneys.
After receiving a kidney transplant, her health began to decline again and a second biopsy found that the new kidney was forming the same type of stones. Her nephrologist knew this meant she likely had a genetic disorder and referred her to Goldfarb, who specializes in underlying genetic causes of kidney stones. A genetic test revealed that the patient had primary hyperoxaluria.
"She would have been treated completely differently if that had been recognized as the cause of her original kidney disease," Goldfarb said. "Now her kidney transplant is getting kidney stones and I'm working with her to prevent that."
Under Goldfarb, the patient will have access to a new experimental drug, called nedosiran, specifically for primary hyperoxaluria, which is currently in clinical trials.
"The kidney doctor that made the diagnosis correctly and referred her to me isn't a kidney stone specialist; he is a general nephrologist who has taken an interest in the topic of kidney stones, recognizing there is sometimes some nuance and specialty of issues related to this," Goldfarb said.
Kaitlin Sullivan is a health, science, and environmental journalist.