Methionine for CaPhos Stone

March 6, 2026 updated by: Ryan L Steinberg

Assessment of L-methionine Supplementation on Urinary pH in Calcium Phosphate Stone Formers

Some kidney stones including calcium phosphate and struvite stones form in vary alkaline urine (high pH). Currently available medication for stone prevention, namely citrate supplementation, can lead to even higher pH levels and promote stone formation. Multiple prior studies have looked at ways to acidify the urine to reduce the risk of recurrent stone formation. Ascorbic acid has been evaluated but showed no reduction in urinary pH. Ammonium chloride has shown to be effective but poorly tolerated (GI upset) at higher doses and thus is not recommended. Most recently, citric acid has been investigated but demonstrated no change in pH as compared to placebo. L-methionine is an amino acid which is metabolized to sulfate and hydrogen ions by the liver, thereby conferring an acid load onto the kidney and in theory can reduce the pH. Prior studies have demonstrated effective acidification of the urine in healthy individuals and amongst struvite stone formers. The purpose of this study is to assess the ability of L-methionine to acidify the urine of calcium phosphate stone formers. The study will involved patients abiding by a short term metabolic diet. The diet consists of typical foods (some frozen, some fresh) that have been carefully balanced to match the recommended/optimal amount of calories, protein, fat, sodium and calcium for a specific body weight. After eating this diet for 2 days, patients will begin taking L-methionine. The metabolic diet will then be resumed for 2 days at the end of taking the L-methionine (both taken together). At various times of the study, urine collections will be performed to see whether the urine becomes more acidic as a result of the L-methionine. If applicable, participants will be asked to undergo drug washout, to begin after consenting. If participants are taking Thiazide diuretics including hydrochlorothiazide, Chlorthalidone, and indapamide and alkali medications including potassium citrate, sodium bicarbonate, sodium citrate, and potassium bicarbonate, they will be asked to stop taking them 5 days before Day 1 of the protocol.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
15

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Any patient, aged 18-90 and not incarcerated, under the care of a urologist at UIHC, with a history of kidney stones with >60% calcium phosphate composition, prior 24 hour urine collection showing a urine pH of >6.1, internet access to complete REDCap surveys

Exclusion Criteria:

  • Any patient over the age of 90 years old, incarcerated or with any one or multiple of the features below:

    • struvite component on prior stone analysis
    • bacteria with urease producing organism at time of stone removal
    • history or evidence of systemic acidosis
    • use of acetazolamide, topiramate, zonisamide, valproic acid
    • Stage >=3 CKD (GFR<60)
    • Hepatic disease
    • Taking thiazide diuretics or alkali and not agreeable to holding medications for the study
    • Pregnancy
    • History of osteoporosis
    • Allergy to methionine, sulfa or sulfa-containing products
    • Allergy to any food products to be provided as part of the study
    • Dietary restrictions that would prevent eating the supplied food such as vegetarian, vegan, gluten free, kosher, etc.
    • Bipolar Disorder
    • Homocystinuria

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Diagnostic
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: L-Methionine
All participants will be given L-Methionine supplements and a special metabolic diet during this protocol.
Dietary supplement: L-Methionine
L-Methionine supplement and metabolic diet

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Time Frame
Urine pH
Time Frame: 11 days
11 days

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Ryan L Steinberg

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
April 1, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
April 1, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
April 1, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
March 6, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 6, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
March 11, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
March 11, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 6, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
March 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 202411458

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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