Influence of Obesity on Endogenous Oxalate Synthesis

March 17, 2026 updated by: Dean Assimos, MD, University of Alabama at Birmingham
There is increasing evidence that obesity is associated with increased urinary oxalate excretion, an important risk factor for calcium oxalate stone formation. By the administration of a controlled low oxalate diet the investigators will estimate endogenous oxalate synthesis in both non-obese and obese non-kidney-stone forming adults. This study seeks to thusly increase the understanding of the relationships between obesity and endogenous oxalate synthesis to serve as a platform to develop novel therapies for stone prevention.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Active, not 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.

Detailed Description

Calcium oxalate stone disease results in billions of dollars in healthcare costs per year, creates large economic losses due to decreased work productivity, and produces significant pain and suffering in affected individuals impacting quality of life. Almost 9% of the population in the United States may now experience a stone event at least once in their lifetime and that figure is increasing. Although stone removing treatments have advanced in the last few decades with a variety of minimally invasive procedures such as shock wave lithotripsy, ureteroscopy and percutaneous nephrolithotomy, our knowledge of how stones form and how to prevent them has not kept pace. Approximately 70-80% of the stones formed contain oxalate. Oxalate is an end product of metabolism and an ubiquitous element of human diets. Small increases in urinary oxalate can increase calcium oxalate crystal formation and thus stone disease. Urinary oxalate levels are affected by both dietary and endogenous components, complicating the discrimination between the two sources. Multiple epidemiological and clinical studies have demonstrated a link between body mass index (BMI) and kidney stone disease and also an increased urinary oxalate excretion.

The interpretation of studies suggesting a link between obesity and the amount of urinary oxalate excreted is confounded by the failure in most studies to use diets controlled in calcium and oxalate. Adult humans without a history of kidney stones will be placed on controlled low oxalate diets to estimate the contribution of endogenous oxalate synthesis to the urinary oxalate pool. In addition, oral doses of 13C2-glycolate and 13C6- vitamin C will be used to determine their conversions to 13C2-oxalate and provide an index of endogenous oxalate production. Body morphometric indices, markers of oxidative stress, and insulin resistance will be assessed in these subjects.They will also be evaluated with DXA and MRI to define body fat content and distribution.

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.
40

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.
  • Name: Sonia Fargue, MD PhD
  • Phone Number: 205-934-0169
  • Email: sfargue@uab.edu

Study Locations

  • United States
    • Alabama
      • Birmingham, Alabama, United States, 35233
        • University of Alabama at Birmingham

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

14 years to 56 years (Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Age 25-60 years
  • Body Mass Index (BMI) <50

Exclusion Criteria:

  • history of kidney stones
  • history of diabetes, hepatic disease, renal disease including Chronic Kidney Disease (CKD), bowel disease or other endocrine disorders
  • pregnant or lactating women, or those with the intention to become pregnant in the near future
  • abnormal liver enzymes
  • hemoglobin A1C > 6.5

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: Prevention
  • Allocation: Non-Randomized
  • Interventional Model: Parallel 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.
Active Comparator: 20-24.9 BMI
Participants with a BMI that falls between 20 and 24.9 who will receive the controlled diet
Dietary supplement: controlled diet
Participants will consume a diet that is controlled in its daily contents of oxalate, calcium, vitamin C and sodium, and in its content of carbohydrate, fat, and protein. Participants will be asked not to take any dietary supplements (vitamins, calcium or other minerals, herbal supplements, nutritional aids), to exercise strenuously, or to consume food or drink that is not provided to them as part of the controlled diet.
Active Comparator: 25-29.9 BMI
Participants with a BMI that falls between 25 and 29.9 who will receive the controlled diet
Dietary supplement: controlled diet
Participants will consume a diet that is controlled in its daily contents of oxalate, calcium, vitamin C and sodium, and in its content of carbohydrate, fat, and protein. Participants will be asked not to take any dietary supplements (vitamins, calcium or other minerals, herbal supplements, nutritional aids), to exercise strenuously, or to consume food or drink that is not provided to them as part of the controlled diet.
Active Comparator: 30-34.9 BMI
Participants with a BMI that falls between 30 and 34.9 who will receive the controlled diet
Dietary supplement: controlled diet
Participants will consume a diet that is controlled in its daily contents of oxalate, calcium, vitamin C and sodium, and in its content of carbohydrate, fat, and protein. Participants will be asked not to take any dietary supplements (vitamins, calcium or other minerals, herbal supplements, nutritional aids), to exercise strenuously, or to consume food or drink that is not provided to them as part of the controlled diet.
Active Comparator: 35-39.9 BMI
Participants with a BMI that falls between 35 and 39.9 who will receive the controlled diet
Dietary supplement: controlled diet
Participants will consume a diet that is controlled in its daily contents of oxalate, calcium, vitamin C and sodium, and in its content of carbohydrate, fat, and protein. Participants will be asked not to take any dietary supplements (vitamins, calcium or other minerals, herbal supplements, nutritional aids), to exercise strenuously, or to consume food or drink that is not provided to them as part of the controlled diet.
Active Comparator: 40-44.9 BMI
Participants with a BMI that falls between 40 and 44.9 who will receive the controlled diet
Dietary supplement: controlled diet
Participants will consume a diet that is controlled in its daily contents of oxalate, calcium, vitamin C and sodium, and in its content of carbohydrate, fat, and protein. Participants will be asked not to take any dietary supplements (vitamins, calcium or other minerals, herbal supplements, nutritional aids), to exercise strenuously, or to consume food or drink that is not provided to them as part of the controlled diet.
Active Comparator: 45-50 BMI
Participants with a BMI that falls between 45 and 50 who will receive the controlled diet.
Dietary supplement: controlled diet
Participants will consume a diet that is controlled in its daily contents of oxalate, calcium, vitamin C and sodium, and in its content of carbohydrate, fat, and protein. Participants will be asked not to take any dietary supplements (vitamins, calcium or other minerals, herbal supplements, nutritional aids), to exercise strenuously, or to consume food or drink that is not provided to them as part of the controlled 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
Measure Description
Time Frame
Urinary oxalate excretion
Time Frame: Baseline through Day 12
Urinary oxalate excretion from 24 hour urine collections will be reported as mg/day.
Baseline through Day 12

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.
University of Alabama at Birmingham

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Dean Assimos, MD, University of Alabama at Birmingham

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 (Actual)

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.
May 24, 2019

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.
August 31, 2026

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.
December 1, 2026

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).
October 3, 2018

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.
October 9, 2018

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.
October 12, 2018

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 19, 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 17, 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.
  • IRB-300002318-P20
  • UAB (Other Identifier: UAB)
  • P20DK119788 (U.S. NIH Grant/Contract)

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

product manufactured in and exported from the U.S.

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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