NCT07225764 · Icahn School of Medicine at Mount Sinai
CaOx Stone Prevention
What this study is about
This single-center randomly assigned controlled trial at Mount Sinai West will enroll 80 patients undergoing percutaneous nephrolithotomy for calcium oxalate stones. Participants will be randomly assigned to receive either empiric therapy or selective therapy guided by 24-hour urine evaluation.
View original scientific description
This single-center randomized controlled trial at Mount Sinai West will enroll 80 patients undergoing percutaneous nephrolithotomy for calcium oxalate stones. Participants will be randomized to receive either empiric therapy or selective therapy guided by 24-hour urine evaluation. The primary outcome is change in calcium oxalate supersaturation at 4 weeks, aiming to determine whether empiric therapy can provide outcomes comparable to selective therapy while simplifying access to prevention.
Interventions
DRUG
Chlorthalidone
Chlorthalidone 25 mg orally once daily is used to reduce urinary calcium excretion and prevent recurrent calcium-containing kidney stones. In this study, it is prescribed either based on stone composition (empiric group) or guided by 24-hour urine results (selective group) for participants meeting criteria for hypercalciuria or calcium oxalate dihydrate stones.
BEHAVIORAL
Low oxalate diet
Participants receive counseling to follow a low oxalate diet, limiting high oxalate foods (\>50 mg/100 g) and restricting moderate oxalate foods (\<50 mg/100 g) to a single four-ounce serving per day. The diet is prescribed either based on stone composition (empiric group) or guided by 24-hour urine results (selective group) for participants with idiopathic hyperoxaluria or calcium oxalate monohydrate stones.
Primary outcome measures
Changes in super saturation of calcium oxalate
Time frame: 4-6 weeks
Change in urine calcium oxalate supersaturation from baseline to the final follow-up visit, measured via 24-hour urine collection. This is a marker that can be predictive of stone episodes, as recurrent stones may take years to develop.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Adult age of 18 years
- Diagnosed with kidney stones and scheduled for PCNL.
- Calcium Oxalate Stone Former
- Pre-operative CT-scan within 90 days of surgery and stone density with \> 1000 Hounsfield units
- Non-pregnant or breastfeeding
- Able and willing to provide informed consent.
- Pre-operative eGFR greater than 70 mL/min/1.73 m² -Negative pre-operative urine culture
Exclusion criteria
- Documented history of gastric or intestinal bypass, liver disease, history of gastrointestinal malabsorptive disease (Crohn's disease, ulcerative colitis, and short-gut syndrome)
- Hyperparathyroidism -Renal tubular acidosis
- Active kidney stone prevention treatment (use of thiazides, alkaline therapy, or low oxalate diet) at the time of surgery
- History of hypokalemia or baseline hypotension
- Allergy to medications used in trial or sulfa-containing medications
- Patient prescribed thiazide, loop diuretics, carbonic anhydrase inhibitors, xanthine oxidase inhibitors, active Vitamin D, bisphosphonates, denosumab, glucocorticoids, or potassium supplementation
Where
- New York, New York
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Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Nov 10, 2025 · Source of record for eligibility and locations