An estimated 1 in 10 Americans will get a kidney stone in their lifetime1. Although kidney stone prevalence has remained relatively stable for men, it has increased by an estimated 3% in women.2 While patients with multiple risk factors for kidney stones may receive broad, generalized advice, preventing recurrence requires precision and an individualized plan. Without targeted diet and lifestyle changes, individuals face a 50% chance of forming another stone within 5 years.3
Nephrologists and dietitians play a critical role in employing strategies to reduce recurrence risk. The clinical team can investigate stone composition in the individual patient, evaluate metabolic contributors, and measure the effectiveness of interventions.
General Dietary Recommendations: A Useful but Broad Foundation
For preventing kidney stones, several dietary principles apply broadly across stone types:2,4
- Increase fluid intake to 2.5-3 liters/day
- Consume 1000-1200 mg/day of calcium
- Limit sodium intake to 2300 mg/day or less
- Moderate animal protein intake
- Increase consumption of citrate-rich foods and beverages
- Increase overall fruit and vegetable intake
- Increase physical activity
To avoid overwhelming patients and focus on interventions likely to have the greatest impact, health care providers need to apply these recommendations in keeping with patients’ metabolic data. Prioritize 24-hour urine testing, then refer patients to dietitians who can guide them through tailored, sustainable changes.
Why the 24-Hour Urinalysis Is Essential
A 24-hour urinalysis is standard of care for kidney stone prevention, and it remains the most effective tool. This test quantifies calcium, oxalate, citrate, sodium, sulfate, phosphate, uric acid, creatinine, urea, and total urine volume.5 Diagnostic services, such as Litholink, can present these results in user-friendly graphic formats that clearly identify risk factors and connect them with targeted interventions. Repeat results are added to the same report, allowing for straightforward comparison over time.6
Despite its efficacy, only 7.4% of patients complete a 24-hour urine collection within 6 months of a symptomatic stone event. Even more concerning, only 16% undergo repeat testing to verify that interventions have successfully reduced metabolic risk. Although patients who see a nephrologist are 3 times more likely to receive testing than those managed solely by other physicians, the overall testing rate indicates a significant gap in standardized care.5 It’s a missed opportunity to prevent pain, complications, and avoidable healthcare spending.5 Metabolic evaluation and targeted treatment are estimated to reduce stone recurrence by up to 90%.
A Strict Low-Oxalate Diet Isn’t Always Best
A low oxalate diet is a common recommendation for those with calcium oxalate stones. However, there are several barriers that make it a frustrating and less effective approach. Food oxalate values are notoriously inaccurate and vary widely depending on the information source. There is currently no evidence-supported daily oxalate limit, and oxalate absorption is heavily influenced by other physiological and dietary factors.7
It’s important to gather 24-hour urine oxalate data; otherwise, a low-oxalate diet may be unnecessarily restrictive without improving outcomes. Even when urinary oxalate is elevated, other factors must be considered: Malabsorption, low calcium intake, microbial imbalance, and other metabolic issues are key factors in hyperoxaluria.8 Dietitians play a crucial role in making these distinctions and ensuring that nutrition prescriptions remain practical and nutritionally sound.
Vitamin C guidance is another area where patients often receive overly restrictive advice. While high-dose vitamin C can increase oxalate formation, evidence provides clear thresholds: Keeping vitamin C intake below 1000 mg/day does not increase stone risk.4
These parameters allow patients who need supplementation for immune or anti-inflammatory support, wound healing, or dietary insufficiency to use vitamin C safely.
Underrecognized Contributors to Recurrent Stones
Some metabolic contributors are overlooked but significantly affect oxalate handling and stone formation.
Fat malabsorption — common with gastric bypass, gallbladder disease, liver dysfunction, thyroid disorders, or dysbiosis — reduces calcium’s availability to bind oxalate in the gut. Unbound oxalate is then more readily absorbed, elevating urinary levels.2,9,10
Historically, recurring urinary tract infections (UTIs) were thought to only increase the risk of struvite stones caused by urease-producing bacteria generating ammonia and raising urinary pH. However, recurrent UTIs are now known to increase calcium-oxalate stone risk as well. Calcium-oxalate stones may develop when bacterial causes of UTI, such as E. coli, degrade citrate, lower the urinary pH, or require frequent antibiotics contributing to dysbiosis and increased oxalate absorption.11–13
Inflammatory bowel disease, small intestinal bacterial overgrowth (SIBO), celiac disease, and microbial imbalances also increase oxalate absorption. These conditions reduce concentrations of beneficial microbes, such as Oxalobacter, Lactobacillus, and Bifidobacterium species, that play a key role in degrading oxalate and maintaining a healthy gut environment.2,9,14
Dietitians Are Key Members of the Prevention Team
Implementing dietary change requires far more than receiving a list of recommendations. Dietitians help patients understand dietary priorities, choose appropriate foods, navigate barriers, and maintain nutritional adequacy. They also integrate 24-hour urinalysis findings into individualized strategies and monitor progress over time. Behavior change is crucial for kidney stone prevention, and dietitians ensure that interventions move beyond instructions and translate into daily practice.
The Importance of Repeat Testing
To confirm the success of interventions, repeat metabolic assessment is essential. Best practice includes:5
- A repeat 24-hour urinalysis within 6 months of making changes
- Annual testing thereafter, once risk is controlled
- Testing every 3 months if stones continue to occur until resolution
This approach identifies persistent risk factors, reinforces adherence, and ensures that preventive strategies remain aligned with metabolic needs.
Action Steps for Nephrology Providers
- Order a 24-hour urinalysis for all recurrent stone formers and first-time stone formers with multiple risk factors.
- Refer patients to a renal dietitian to ensure accurate, sustainable implementation of nutrition recommendations.
- Avoid relying on blanket oxalate or vitamin C restriction without urine data indicating a need.
- Evaluate patients for malabsorption, gut dysbiosis, and recurrent UTIs.
- Repeat 24-hour urine testing within 6 months and continue with annual — or more frequent — retesting depending on stone recurrence.
- Educate patients on the value of metabolic testing, emphasizing its potential to reduce recurrence by up to 90%.
Recurrent stone prevention is most successful when guided by metabolic data, supported by dietitians, and monitored through regular retesting as ordered by nephrologists. Incorporating these steps into routine care has the power to dramatically reduce stone burden and improve long-term patient health and quality of life.
Read More: Kidney Stone Diagnosis & Treatment Updates