June 20, 2024
Kidney stones, also referred to as renal calculi, nephrolithiasis or urolithiasis, are hard deposits made of minerals and salts that form inside of the kidneys. Kidney stones have a variety of causes including environmental, dietary, hormonal and genetic components.
Kidney stones are common, with a lifetime prevalence of 5% to 10%. Although less data is currently available, some evidence suggests that the incidence and prevalence of stone disease in children is increasing. A U.S. study found that the incidence of symptomatic kidney stones in children increased from 7.9 per 100,000 in 1996 to 18.5 per 100,000 in 2007, with the fastest rate of increase among adolescent girls. Study results were published in 2022 in Nature Reviews Nephrology.
"Years ago, it was rare to see kidney stones in children," says David J. Sas, D.O., a pediatric nephrologist at Mayo Clinic in Rochester, Minnesota. "But the data is clear. In the past two decades, the prevalence has been on the rise. We've done a lot of work to identify genetic and environmental factors that contribute to kidney stone formation in children, and our goal is to improve strategies for prevention and treatment."
Symptoms
If a kidney stone becomes lodged in one of the ureters, it may block the flow of urine and cause the kidney to swell and the ureter to spasm. This can be very painful and patients can experience the following symptoms:
- Severe, sharp pain in the side and back.
- Pain that radiates to the lower abdomen and groin.
- Pain that comes in waves and fluctuates in intensity.
- Pain or burning sensation while urinating.
Other signs and symptoms can include:
- Pink, red or brown urine.
- Urinating more often than usual, urinating in small amounts or having a persistent need to urinate.
- Nausea and vomiting.
- Fever and chills if an infection is present.
Diagnosis
"Certainly, any child with kidney stones should be referred to a pediatric nephrologist or urologist with expertise in kidney stone disease," explains Dr. Sas. "After any acute needs are met, a pediatric nephrologist can help ascertain the likely cause of the stones and how to manage it moving forward."
Each pediatric nephrologist collaborates closely with other specialists, including urologists, radiologists, dietitians and others as needed to diagnose each patient's condition and develop an individualized treatment plan. These plans include offering advanced diagnostic imaging and laboratory tests to help determine the type of the kidney stone and the patient's underlying risk factors.
Types of kidney stones include:
- Calcium stones. Most kidney stones are calcium stones, usually in the form of calcium oxalate and, less commonly, calcium phosphate.
- Struvite stones. Struvite stones form in response to a urinary tract infection. These stones can grow quickly and become quite large, sometimes with few symptoms or little warning.
- Uric acid stones. Uric acid stones are very rare in children but can form in people who lose too much fluid because of chronic diarrhea or malabsorption, those who eat a high-protein diet, and those with diabetes or metabolic syndrome. Certain genetic factors also may increase the risk of uric acid stones.
- Cystine stones. These stones form in people with a hereditary disorder called cystinuria that causes the kidneys to excrete too much of a specific amino acid.
Factors that increase the risk of developing kidney stones include:
- Family or personal history.
- Dehydration.
- Certain diets.
- Digestive diseases and surgery.
- Other medical conditions such as renal tubular acidosis, cystinuria, hyperparathyroidism and repeated urinary tract infections also can increase the risk of kidney stones.
- Certain supplements and medications.
- Anatomical abnormalities of the kidneys or urinary tract.
Treatment and prevention
"Treatment strategies can vary greatly depending on each patient's underlying risk factors — whether genetic or otherwise," says Dr. Sas. "It's very important to understand what type of stone the patient is forming and the cause in order to create an individualized treatment plan."
For smaller stones, treatment options for acute episodes can include pain relievers, fluid administration and medications that can help stones pass. Kidney stones that are too large to pass on their own or that cause obstruction, kidney damage or ongoing urinary tract infections may require more-extensive treatment.
"Depending on stone size and its location within the urinary tract, pediatric urologists may need to surgically break up and remove the stone," says Candace F. Granberg, M.D., a pediatric urologist at Mayo Clinic in Rochester, Minnesota. "If a patient has a stone that is blocking urine flow, and they also have a fever, they require urgent surgery to relieve the obstruction." Treatments include ureteroscopy, laser lithotripsy, extracorporeal shock wave lithotripsy or other surgical interventions.
The proper, individualized prevention strategy can only be developed once a comprehensive evaluation, including a 24-hour urine collection, has been performed and interpreted by an expert. Depending on the results of this evaluation, prevention follow-up care can include a combination of lifestyle changes and medications. Lifestyle changes include drinking more water, eating a low-salt diet and, in some cases, making other specific dietary changes. Medications can control the amounts of minerals and salts in the urine and might be helpful in people who form certain kinds of stones.
"Some of this follow-up care can certainly be done remotely," says Dr. Sas. "We work with patients and their referring providers to ensure everything is done as thoroughly and conveniently as possible."
For more information
Singh P, et al. The genetics of kidney stone disease and nephrocalcinosis. Nature Reviews Nephrology. 2022;18:224.
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