Chlorthalidone + Low Oxalate Diet for Kidney Stones

Age: 18+

Sex: Any

Trial Phase: Phase 4

Sponsor: Icahn School of Medicine at Mount Sinai

Must not be taking: Thiazides, Loop diuretics, others

Disqualifiers: Gastric bypass, Liver disease, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Prior Safety Data This treatment has passed at least one previous human trial

Compensation: Varies

Number of Visits: 2

Duration: 4 weeks

80 Participants Needed

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial explores new methods to prevent kidney stones, specifically calcium oxalate stones, by testing a combination of chlorthalidone (a type of diuretic) and a low oxalate diet. Researchers aim to determine if a simpler approach, without detailed urine analysis, can be as effective as a more customized treatment plan. It is ideal for individuals diagnosed with calcium oxalate kidney stones who are scheduled for a procedure called percutaneous nephrolithotomy (PCNL). As a Phase 4 trial, this study involves an FDA-approved treatment and seeks to understand how it benefits a broader range of patients.

Do I need to stop my current medications for the trial?

Yes, if you are currently on thiazides, loop diuretics, or certain other medications like glucocorticoids or potassium supplements, you will need to stop them to participate in the trial.

What is the safety track record for these treatments?

Research has shown that chlorthalidone is a well-tolerated option for preventing kidney stones. Studies indicate it can lower the chance of recurrence and effectively prevent stones. Some studies specifically mention that taking chlorthalidone at doses of 25 or 50 mg daily can successfully reduce the recurrence of kidney stones.

Patients might experience side effects like dizziness or changes in electrolyte levels, but these are usually manageable. Importantly, chlorthalidone is already approved for treating other conditions, like high blood pressure, which adds reassurance about its safety.

Regarding the low oxalate diet, research suggests it can help reduce the formation of kidney stones. This diet involves eating fewer foods high in oxalates, compounds that can lead to stones. It has been effective in reducing stone recurrence for many patients without causing significant side effects.

Overall, both treatments have shown safety with minimal side effects for most patients. ^{1 2 3 4 5}

Why are researchers enthusiastic about this study treatment?

Most treatments for kidney stones involve pain management and waiting for stones to pass naturally, or in some cases, surgical removal. However, researchers are excited about the combination of chlorthalidone and a low oxalate diet because it offers a proactive approach. Chlorthalidone is a diuretic that reduces calcium levels in urine, potentially decreasing stone formation, while the low oxalate diet targets one of the primary components of these stones. This dual approach not only targets the cause but may also prevent the recurrence of stones, offering a preventative strategy that current treatments do not typically address.

What evidence suggests that this trial's treatments could be effective for kidney stones?

Studies have shown that chlorthalidone, a long-lasting water pill, effectively prevents calcium kidney stones. It helps the kidneys eliminate more salt and water, reducing the likelihood of stone formation. Research also indicates that a low-oxalate diet, which decreases oxalate in the urine, can lower the risk of kidney stones. Patients on this diet have experienced fewer recurrences of kidney stones. In this trial, participants in the empiric therapy arm may receive chlorthalidone, a low-oxalate diet, or both, depending on their stone composition. The selective therapy arm will tailor treatment based on specific urine analysis results, offering a comprehensive approach to prevention. ^{1 3 5 6 7}

Who Is on the Research Team?

Mantu Gupta, MD

Principal Investigator

Mount Sinai West

Are You a Good Fit for This Trial?

This trial is for patients with calcium oxalate kidney stones who are undergoing a specific surgical procedure called percutaneous nephrolithotomy. It's not clear what the exclusion criteria are, but typically participants would need to meet certain health standards and be able to follow the study protocol.

Inclusion Criteria

Able and willing to provide informed consent

Non-pregnant or breastfeeding

I am 18 years old or older.

Exclusion Criteria

Allergy to medications used in trial or sulfa-containing medications

Documented history of gastric or intestinal bypass

I have a liver condition.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Treatment

Participants receive either empiric therapy or selective therapy based on 24-hour urine evaluation

4 weeks

1 visit (in-person) for randomization and treatment initiation

Follow-up

Participants are monitored for changes in calcium oxalate supersaturation and other urinary markers

4-6 weeks

1 visit (in-person) for final follow-up and assessment

What Are the Treatments Tested in This Trial?

Interventions

• Chlorthalidone
• Low oxalate diet

Trial Overview The study at Mount Sinai West is testing two approaches to prevent kidney stones from coming back: one group will get a water pill called Chlorthalidone and follow a low oxalate diet without further tests, while another group's treatment will be based on their urine test results.

How Is the Trial Designed?

Group I: Empiric Therapy Experimental Treatment 2 Interventions

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.

Group II: Selective Therapy Active Control 2 Interventions

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.

Who Is Running the Clinical Trial?

Icahn School of Medicine at Mount Sinai

Lead Sponsor

Trials

933

Recruited

579,000+

Citations

1. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC12314834/

Indapamide or chlorthalidone to reduce urine supersaturation ... The purpose of this study is to assess if indapamide or chlorthalidone is a promising candidate compound for reducing the risk of kidney stone ...

2. healio.com healio.com/news/nephrology/20250411/longacting-diuretic-chlorthalidone-may-increase-kidney-stone-risk

Long-acting diuretic chlorthalidone may increase kidney ... The main outcome was the occurrence of kidney stones, tracked over a mean 4.2 years. Researchers found no substantial differences in new kidney ...

3. auajournals.org auajournals.org/doi/10.1097/JU.0000000000004562

Effect of Chlorthalidone and Hydrochlorothiazide on 12- ... We conclude that CTD is a longer acting and more effective agent for prevention of calcium kidney stones, although varying dose timing for a ...

4. medscape.com medscape.com/viewarticle/chlorthalidone-increases-kidney-stone-recurrence-2025a10008qn

Chlorthalidone Increases Kidney Stone Recurrence With an average follow-up of 4.2 years, no significant differences were observed between the two groups in the development of new kidney stone ...

5. pubmed.ncbi.nlm.nih.gov pubmed.ncbi.nlm.nih.gov/40523783/

Indapamide or chlorthalidone to reduce urine ... The study targets enrolment of 99 participants to achieve 80% power for detecting a 20% reduction in the relative supersaturation ratios of ...

6. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC8076055/

Chlorthalidone with potassium citrate decreases calcium ... Chlorthalidone with potassium citrate decreases calcium oxalate stones and increases bone quality in genetic hypercalciuric stone-forming rats - PMC.

7. journals.lww.com journals.lww.com/co-nephrolhypertens/fulltext/2024/07000/thiazides_for_kidney_stone_recurrence_prevention.11.aspx

Thiazides for kidney stone recurrence prevention Both indapamide (at a dose of 2.5 mg daily) and chlorthalidone (at doses of 25 or 50 mg daily) reduced kidney stone recurrence in one past RCT each [14,15]. ...