Kidney StoneNCT03704350
Influence of Obesity on Endogenous Oxalate Synthesis
A study of Kidney Stone, run by University of Alabama at Birmingham at 1 site in United States.
Trial summary
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… Read more about this study
- Who is it for?
- Ages 18 to 60 yearsHealthy volunteers can take part
- Conditions the study is for
- Kidney Stone
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 40 participants
- Where
- 1 siteUnited States
- Study dates
- 24 May 2019to 1 Dec 2026
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
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 to 60 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Age 25-60 years
- Body Mass Index (BMI) <50
Who cannot join
- 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
Trial locations and contacts
1 site in 1 country.
United States1 site
University of Alabama at Birmingham
Birmingham, Alabama, 35233
About this study
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.
Read the 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.
- Conditions
- Kidney Stone
- Being tested
- controlled diet
- Medical subject headings
- Kidney Calculi
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
controlled dietDietary supplement
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.
| Study group | Role | What they receive |
|---|---|---|
| 20-24.9 BMI | Active comparator | Participants with a BMI that falls between 20 and 24.9 who will receive the controlled diet Receives: Dietary Supplement: controlled diet |
| 25-29.9 BMI | Active comparator | Participants with a BMI that falls between 25 and 29.9 who will receive the controlled diet Receives: Dietary Supplement: controlled diet |
| 30-34.9 BMI | Active comparator | Participants with a BMI that falls between 30 and 34.9 who will receive the controlled diet Receives: Dietary Supplement: controlled diet |
| 35-39.9 BMI | Active comparator | Participants with a BMI that falls between 35 and 39.9 who will receive the controlled diet Receives: Dietary Supplement: controlled diet |
| 40-44.9 BMI | Active comparator | Participants with a BMI that falls between 40 and 44.9 who will receive the controlled diet Receives: Dietary Supplement: controlled diet |
| 45-50 BMI | Active comparator | Participants with a BMI that falls between 45 and 50 who will receive the controlled diet. Receives: Dietary Supplement: controlled diet |
What is being measured
The primary outcome is the main question the study is designed to answer.
Urinary oxalate excretion
Urinary oxalate excretion from 24 hour urine collections will be reported as mg/day.
Measured: Baseline through Day 12
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted12 Oct 2018
- Study start24 May 2019
- Primary completion31 Aug 2026 (estimated)
- Study completion1 Dec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Kidney StoneStudies of the same condition, open and under way.
- More trials run by University of Alabama at BirminghamThe 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 N/A
- Primary purpose
- Prevention
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 40 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Alabama at Birmingham
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Dean Assimos, MD, University of Alabama at Birmingham
- Investigators
- Dean Assimos, MD, Principal investigator, University of Alabama at Birmingham
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03704350
- Sponsor's protocol ID
- IRB-300002318-P20
- Other IDs
- P20DK119788, UAB
- Status last verified
- Mar 2026
- First submitted
- 3 Oct 2018
- Last updated
- 19 Mar 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 19 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Influence of Obesity on Endogenous Oxalate Synthesis
- ClinicalTrials.gov ID
- NCT03704350
- Acronym / sponsor ID
- IRB-300002318-P20
- Conditions
- Kidney Stone
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 40 participants (estimated)
- Lead sponsor
- University of Alabama at BirminghamUniversity, hospital or other
- Collaborators
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
- Study start
- 24 May 2019 (actual)
- Primary completion
- 31 Aug 2026 (estimated)
- Study completion
- 1 Dec 2026 (estimated)
- First posted
- 12 Oct 2018 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
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 design
- Primary purpose
- Prevention
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 6
| Arm | Type | Receives |
|---|---|---|
| 20-24.9 BMI | Active comparator | Dietary Supplement: controlled dietParticipants with a BMI that falls between 20 and 24.9 who will receive the controlled diet |
| 25-29.9 BMI | Active comparator | Dietary Supplement: controlled dietParticipants with a BMI that falls between 25 and 29.9 who will receive the controlled diet |
| 30-34.9 BMI | Active comparator | Dietary Supplement: controlled dietParticipants with a BMI that falls between 30 and 34.9 who will receive the controlled diet |
| 35-39.9 BMI | Active comparator | Dietary Supplement: controlled dietParticipants with a BMI that falls between 35 and 39.9 who will receive the controlled diet |
| 40-44.9 BMI | Active comparator | Dietary Supplement: controlled dietParticipants with a BMI that falls between 40 and 44.9 who will receive the controlled diet |
| 45-50 BMI | Active comparator | Dietary Supplement: controlled dietParticipants with a BMI that falls between 45 and 50 who will receive the controlled diet. |
Who may qualify
- Ages
- 18 to 60 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (2 listed)
- Age 25-60 years
- Body Mass Index (BMI) <50
Key exclusion criteria (5 listed)
- 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| controlled dietParticipants 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. | Dietary supplement | 20-24.9 BMI, 25-29.9 BMI, 30-34.9 BMI, 35-39.9 BMI, 40-44.9 BMI, 45-50 BMI |
Primary outcome
Urinary oxalate excretion
Time frame: Baseline through Day 12
Urinary oxalate excretion from 24 hour urine collections will be reported as mg/day.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 19 Mar 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Dean Assimos, MD principal investigator
University of Alabama at Birmingham
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study of Kidney Stone, run by University of Alabama at Birmingham at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 2 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: under way, not looking for participants, as of the sponsor's last update on 19 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Urinary oxalate excretion (time frame: Baseline through Day 12). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 19 Mar 2026.