Kidney StonesPhase 4NCT07225764
CaOx Stone Prevention
A Phase 4 study testing Chlorthalidone and Low oxalate diet in people with Kidney Stones, run by Icahn School of Medicine at Mount Sinai at 1 site in United States.
Trial summary
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. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Kidney Stones
- What is being tested?
- Chlorthalidone and Low oxalate diet
- Type of treatment
- Pill or oral medicine, Lifestyle or therapy programme
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 80 participants
- Where
- 1 siteUnited States
- Study dates
- 23 Oct 2025to 31 Dec 2027
- Phase
- Phase 4
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- 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
Who cannot join
- 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
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
Mount Sinai West
New York, New York, 10019
Mantu Gupta, MD, 212-241-1272, mantu.gupta@mountsinai.org
Blair Gallante, MPH, 631-991-1159, blair.gallante@mountsinai.org
About this study
Official title: Empiric vs Selective Medical Therapy for Calcium Oxalate Stone Prevention: A Randomized Controlled Trial
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.
Read the detailed description
This is a single-center, randomized controlled trial evaluating the effectiveness of empiric versus selective medical therapy for the prevention of calcium oxalate kidney stones. The study will enroll 80 patients at Mount Sinai West undergoing percutaneous nephrolithotomy (PCNL) for predominantly calcium oxalate stones. Participants will be randomized postoperatively to receive either empiric therapy (based on stone composition and urinalysis) or selective therapy (based on 24-hour urine metabolic evaluation). The primary endpoint is the change in calcium oxalate supersaturation (ssCaOx) at 4 weeks post-treatment. The study is designed to determine whether an empiric approach can achieve comparable outcomes to selective therapy while simplifying access to preventive treatment.
- Conditions
- Kidney Stones
- Being tested
- Chlorthalidone, Low oxalate diet
- Keywords
- kidney stones, calcium oxalate, nephrolithiasis
- Medical subject headings
- Kidney Calculi, Nephrolithiasis
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
ChlorthalidoneDrug
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.
Low oxalate dietBehavioural
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.
| Study group | Role | What they receive |
|---|---|---|
| Empiric Therapy | Experimental | Patients randomized to the empiric group will receive treatment based on the pH on urinalysis and stone composition. Patients with greater than 50% calcium oxalate monohydrate (COM) stone composition will be counseled on a low oxalate diet by a medical provider. Patients with greater than 50% calcium oxalate dihydrate (COD) stone composition will be prescribed 25 mg of chlorthalidone once a day. In the rare event the stone composition is 50% COM and 50% COD, then those patients will receive both low oxalate diet counseling and a prescription for chlorthalidone. Receives: Drug: Chlorthalidone; Behavioral: Low oxalate diet |
| Selective Therapy | Active comparator | Patients randomized to the selective group will undergo medical therapy based on the American Urological Association (AUA) guidelines from the 24-hour urine collection results. Patients with idiopathic hyperoxaluria (> 40mg/day) will receive a low oxalate diet and receive the same dietary counseling, handout, and questionnaire as the empiric group. Patients with idiopathic hypercalciuria (> 250mg in men, >200mg in women) will be prescribed 25mg of chlorthalidone once a day. Receives: Drug: Chlorthalidone; Behavioral: Low oxalate diet |
What is being measured
The primary outcome is the main question the study is designed to answer.
Changes in super saturation of calcium oxalate
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.
Measured: 4-6 weeks
Secondary outcomes (3)
Changes in urinary oxalate levels
Difference in 24-hour urinary oxalate excretion from baseline to the final follow-up visit, measured in mg/day, to assess the effect of dietary and pharmacologic interventions on oxalate levels.
Measured: 4-6 weeks
Changes in urinary calcium levels
Difference in 24-hour urinary calcium excretion from baseline to the final follow-up visit, measured in mg/day, to evaluate the effect of chlorthalidone and dietary interventions on urinary calcium levels.
Measured: 4-6 weeks
Chlorthalidone Adherence Survey (adapted from Brief Medication Questionnaire)
Participant-reported adherence to prescribed chlorthalidone therapy, assessed via a structured survey at the follow-up visit, to evaluate compliance with the study intervention.
Response will be either 0=nonadherent or 1=adherent.
Measured: 4-6 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted10 Nov 2025
- Study start23 Oct 2025
- Primary completion31 Dec 2027 (estimated)
- Study completion31 Dec 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Kidney StonesStudies of the same condition, open and under way.
- More trials run by Icahn School of Medicine at Mount SinaiThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 4
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 80 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Icahn School of Medicine at Mount Sinai
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Mantu Gupta, Icahn School of Medicine at Mount Sinai
- Investigators
- Mantu Gupta, MD, Principal investigator, Mount Sinai West
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07225764
- Sponsor's protocol ID
- STUDY-25-00784
- Status last verified
- Aug 2026
- First submitted
- 5 Nov 2025
- Last updated
- 14 Aug 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No: Individual participant data will not be shared because all results are part of standard clinical care, and participants have access to their own medical records.