Kidney StonesNCT06989320
Endogenous Oxalate Synthesis in Idiopathic Calcium Oxalate Kidney Stone Disease
A study testing Low-oxalate diet and glycolate dosing, Oral glycolate dosing and Oral 13C- ascorbic acid dosing in people with Kidney Stones and Kidney Calculi, run by University of Alabama at Birmingham at 2 sites in United States.
Trial summary
The goal of this clinical trial study is to test if patients with idiopathic calcium oxalate kidney stones have an increased production of oxalate by the body, which would lead to increased urinary excretion of oxalate. Read more about this study
- Who is it for?
- Ages 18 to 80 yearsHealthy volunteers can take part
- Conditions the study is for
- Kidney Stones, Kidney Calculi, Urolithiasis
- What is being tested?
- Low-oxalate diet and glycolate dosing, Oral glycolate dosing and Oral 13C- ascorbic acid dosing
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 80 participants
- Where
- 2 sitesUnited States
- Study dates
- 27 May 2025to 31 Dec 2031
- 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 80 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- age 18-80 yrs
- Body Mass Index > 18.5 kg/m2
- Normal fasting serum electrolytes on comprehensive metabolic profile
- Willing to ingest fixed diets
- Willing to stop supplements (vitamins including vitamin C, calcium (citrate or carbonate) and other minerals, herbal supplements, nutritional aids, probiotics) for 2 weeks before start and during study.
- For stone formers: first time or recurrent Calcium Oxalate stone former. Composition of most recent stone ≥ 50% calcium oxalate if available, uric acid component <20%
Who cannot join
- Chronic Kidney Disease stage 4-5
- Primary hyperoxaluria, Enteric (secondary) hyperoxaluria
- Liver, bowel, endocrine or renal diseases (other than idiopathic Calcium Oxalate kidney stones) or any other condition that may influence the absorption, transport or urinary excretion of ions, which will compromise the interpretation of results, including: Cystic fibrosis, Celiac disease, Cystinuria, Uric acid stone former, Nephrotic syndrome, Sarcoidosis, Renal tubular acidosis, Primary hyperparathyroidism, Neurogenic bladder, Urinary diversion, Chronic diarrhea, Bariatric surgery, Inflammatory bowel disease
- Pregnancy or breast-feeding
- Incompatible dietary requirements with the study, food allergies or intolerance to any of the foods in study menus
- Active malignancy or treatment for malignancy within 12 months prior to screening
Show all 9Show fewer
- Utilization of immunosuppressive medication
- Uncontrolled hypertension or diabetes
- Diabetes type 1
Trial locations and contacts
2 sites in 1 country. Contact the study team or a site near you to ask about taking part.
United States2 sites, 2 recruiting
- Recruiting
United States, Alabama University of Alabama at Birmingham
Birmingham, Alabama, 35294
Sonia Fargue, PhD, 205-975-6932, sfargue@uabmc.edu
Research Coordinator, 205-934-5712, kidneystone@uabmc.edu
- Not yet recruiting
University of Texas South Western Medical Center
Dallas, Texas, 75390
Naim Maalouf, MD, Naim.Maalouf@UTSouthwestern.edu
Research Coordinator, Esperanza.Jackson@UTSouthwestern.edu
About this study
Official title: Endogenous Oxalate Synthesis in Idiopathic Calcium Oxalate Kidney Stone Formers
The goal of this clinical trial study is to test if patients with idiopathic calcium oxalate kidney stones have an increased production of oxalate by the body, which would lead to increased urinary excretion of oxalate.
The study will recruit adult patients with a history of calcium oxalate kidney stones and healthy volunteers without kidney stones.
Participants will
ingest fixed diets containing low amounts of oxalate for 5 days ingest a soluble form of glycolate and vitamin C collect urine, blood, stool during the dietary and oral dosing portions of the study and also collect breath sample during the oral glycolate test
Read the detailed description
In this study the investigators propose to measure the production of oxalate by the body (endogenous oxalate synthesis), after equilibration on a low oxalate diet (<60 mg oxalate/day, 600-800 mg calcium/day) and estimate the importance of vitamin C and glycolate metabolism to oxalate production in both Calcium Oxalate Kidney Stone patients and matched controls by oral dosings of those two substances.
Phase 1. Screening and low-oxalate diet 24-hr urinary excretions. Between the University of Alabama at Birmingham (UAB) and the University of Texas Southwestern Medical Center (UTSW), the study will enroll 40 subjects with idiopathic Calcium Oxalate Kidney Stone (20 Males/20 Females) and 40 non-kidney stone forming controls (20 Males/20 Females). Participants in the two groups will be matched for age (within 10 yrs) and gender. Screening will include blood complete metabolic profile and two 24-hour urine specimens collected at home on self-choice diets and anthropometric measurements.
Participants will then ingest the controlled low-oxalate (<60 mg/day) diet for 5 consecutive days and collect two 24-hour urines after 2 days of dietary equilibration.
Phase 2. Oxalate production and 13C-glycolate dosing tests. On Day 5, participants will arrive after an overnight fast in the research unit to undergo the oral 13C-glycolate dosing test. After a 1-hour baseline urine collection, they will ingest an oral load containing 0.5 mg/kg body weight of 13C-glycolate, dissolved in bottled water. For the next 7 hours, blood and urine will be collected hourly, and breath as more time points. They will remain on the fixed diet for 24 hours with a meal 7 hours post-load, and dinner at home 12 hours post-load. They will collect the remainder of their 24-hour urine at home.
Phase 3. Oxalate production and 13C-ascorbic acid dosing tests. After 1 day of equilibration on the same low-oxalate diet, participants will arrive after an overnight fast in the research unit to provid eone blood and one urine sample and then ingest an oral dose of 13C-ascorbic acid (0.75 mg/kg), return home and continue to ingest the low-oxalate diet. The next morning, participants will arrive after an overnight fast in the research unit. For the next 7 hours, blood and urine will be collected hourly. They will remain on the fixed diet for 24 hours with a meal at the end of the visit.
- Conditions
- Kidney Stones, Kidney Calculi, Urolithiasis, Urolithiasis, Calcium Oxalate, Nephrolithiasis, Nephrolithiasis, Calcium Oxalate
- Being tested
- Low-oxalate diet and glycolate dosing, Oral glycolate dosing, Oral 13C- ascorbic acid dosing
- Keywords
- oxalate synthesis
- Medical subject headings
- Kidney Calculi, Urolithiasis, Nephrolithiasis, Calcium Oxalate, Nephrolithiasis
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Low-oxalate diet and glycolate dosingDietary supplement
Low-oxalate diet 4 days of fixed eucaloric diet with low oxalate (<60 mg/day), normal calcium content (600-1000 mg/day)
Oral glycolate dosingDietary supplement
Oral 13C-glycolate dosing (0.5 mg/kg)
Oral 13C- ascorbic acid dosingDietary supplement
Oral 13C- ascorbic acid dosing (0.75 mg/kg)
| Study group | Role | What they receive |
|---|---|---|
| Idiopathic Calcium Oxalate Kidney Stone Patients | Experimental | Low oxalate fixed diets. oral glycolate and ascorbic acid administration Receives: Dietary Supplement: Low-oxalate diet and glycolate dosing; Dietary Supplement: Oral glycolate dosing; Dietary Supplement: Oral 13C- ascorbic acid dosing |
| Healthy non-kidney stone forming individuals | Active comparator | Low oxalate fixed diets. oral glycolate and ascorbic acid administration Receives: Dietary Supplement: Low-oxalate diet and glycolate dosing; Dietary Supplement: Oral glycolate dosing; Dietary Supplement: Oral 13C- ascorbic acid dosing |
What is being measured
The primary outcome is the main question the study is designed to answer.
Estimated endogenous oxalate synthesis (oxalate mg/day)
Basal rate of endogenous oxalate synthesis estimated by repeat fasted hourly urine collections (mg/day)
Measured: 1 day
Secondary outcomes (2)
24-hour urinary oxalate excretion on low oxalate diet
mean 24-hour urinary oxalate excretion on the low oxalate diet (mg/day)
Measured: 2 days
contribution of ascorbic acid breakdown to urinary oxalate excretion
contribution of ascorbic acid breakdown to oxalate synthesis (%)
Measured: 2 days
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted25 May 2025
- Study start27 May 2025
- Primary completion31 Dec 2030 (estimated)
- Study completion31 Dec 2031 (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 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
- Basic science
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 80 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Alabama at Birmingham
- Sponsor type
- University, hospital or other
- Collaborators
- University of Texas, Southwestern Medical Center at Dallas, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
- Responsible party
- Principal investigator, Sonia Fargue, University of Alabama at Birmingham
- Investigators
- Sonia Fargue, PhD, Principal investigator, University of Alabama at Birmingham
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06989320
- Sponsor's protocol ID
- IRB300014279-OSS
- Other IDs
- R01DK137784
- Status last verified
- Aug 2026
- First submitted
- 9 May 2025
- Last updated
- 27 Aug 2026
- Results posted
- No
- Data monitoring committee
- Yes
- 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 27 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Endogenous Oxalate Synthesis in Idiopathic Calcium Oxalate Kidney Stone Formers
- ClinicalTrials.gov ID
- NCT06989320
- Acronym / sponsor ID
- IRB300014279-OSS
- Conditions
- Kidney Stones, Kidney Calculi, Urolithiasis, Urolithiasis, Calcium Oxalate, Nephrolithiasis, Nephrolithiasis, Calcium Oxalate
- Keywords
- oxalate synthesis
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 80 participants (estimated)
- Lead sponsor
- University of Alabama at BirminghamUniversity, hospital or other
- Collaborators
- University of Texas, Southwestern Medical Center at Dallas, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
- Study start
- 27 May 2025 (actual)
- Primary completion
- 31 Dec 2030 (estimated)
- Study completion
- 31 Dec 2031 (estimated)
- First posted
- 25 May 2025 (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.
The goal of this clinical trial study is to test if patients with idiopathic calcium oxalate kidney stones have an increased production of oxalate by the body, which would lead to increased urinary excretion of oxalate.
The study will recruit adult patients with a history of calcium oxalate kidney stones and healthy volunteers without kidney stones.
Participants will
ingest fixed diets containing low amounts of oxalate for 5 days ingest a soluble form of glycolate and vitamin C collect urine, blood, stool during the dietary and oral dosing portions of the study and also collect breath sample during the oral glycolate test
Detailed description
In this study the investigators propose to measure the production of oxalate by the body (endogenous oxalate synthesis), after equilibration on a low oxalate diet (<60 mg oxalate/day, 600-800 mg calcium/day) and estimate the importance of vitamin C and glycolate metabolism to oxalate production in both Calcium Oxalate Kidney Stone patients and matched controls by oral dosings of those two substances.
Phase 1. Screening and low-oxalate diet 24-hr urinary excretions. Between the University of Alabama at Birmingham (UAB) and the University of Texas Southwestern Medical Center (UTSW), the study will enroll 40 subjects with idiopathic Calcium Oxalate Kidney Stone (20 Males/20 Females) and 40 non-kidney stone forming controls (20 Males/20 Females). Participants in the two groups will be matched for age (within 10 yrs) and gender. Screening will include blood complete metabolic profile and two 24-hour urine specimens collected at home on self-choice diets and anthropometric measurements.
Participants will then ingest the controlled low-oxalate (<60 mg/day) diet for 5 consecutive days and collect two 24-hour urines after 2 days of dietary equilibration.
Phase 2. Oxalate production and 13C-glycolate dosing tests. On Day 5, participants will arrive after an overnight fast in the research unit to undergo the oral 13C-glycolate dosing test. After a 1-hour baseline urine collection, they will ingest an oral load containing 0.5 mg/kg body weight of 13C-glycolate, dissolved in bottled water. For the next 7 hours, blood and urine will be collected hourly, and breath as more time points. They will remain on the fixed diet for 24 hours with a meal 7 hours post-load, and dinner at home 12 hours post-load. They will collect the remainder of their 24-hour urine at home.
Phase 3. Oxalate production and 13C-ascorbic acid dosing tests. After 1 day of equilibration on the same low-oxalate diet, participants will arrive after an overnight fast in the research unit to provid eone blood and one urine sample and then ingest an oral dose of 13C-ascorbic acid (0.75 mg/kg), return home and continue to ingest the low-oxalate diet. The next morning, participants will arrive after an overnight fast in the research unit. For the next 7 hours, blood and urine will be collected hourly. They will remain on the fixed diet for 24 hours with a meal at the end of the visit.
Study design
- Primary purpose
- Basic science
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Idiopathic Calcium Oxalate Kidney Stone Patients | Experimental | Dietary Supplement: Low-oxalate diet and glycolate dosing, Dietary Supplement: Oral glycolate dosing, Dietary Supplement: Oral 13C- ascorbic acid dosingLow oxalate fixed diets. oral glycolate and ascorbic acid administration |
| Healthy non-kidney stone forming individuals | Active comparator | Dietary Supplement: Low-oxalate diet and glycolate dosing, Dietary Supplement: Oral glycolate dosing, Dietary Supplement: Oral 13C- ascorbic acid dosingLow oxalate fixed diets. oral glycolate and ascorbic acid administration |
Who may qualify
- Ages
- 18 to 80 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (6 listed)
- age 18-80 yrs
- Body Mass Index > 18.5 kg/m2
- Normal fasting serum electrolytes on comprehensive metabolic profile
- Willing to ingest fixed diets
- Willing to stop supplements (vitamins including vitamin C, calcium (citrate or carbonate) and other minerals, herbal supplements, nutritional aids, probiotics) for 2 weeks before start and during study.
Key exclusion criteria (9 listed)
- Chronic Kidney Disease stage 4-5
- Primary hyperoxaluria, Enteric (secondary) hyperoxaluria
- Liver, bowel, endocrine or renal diseases (other than idiopathic Calcium Oxalate kidney stones) or any other condition that may influence the absorption, transport or urinary excretion of ions, which will compromise the interpretation of results, including: Cystic fibrosis, Celiac disease, Cystinuria, Uric acid stone former, Nephrotic syndrome, Sarcoidosis, Renal tubular acidosis, Primary hyperparathyroidism, Neurogenic bladder, Urinary diversion, Chronic diarrhea, Bariatric surgery, Inflammatory bowel disease
- Pregnancy or breast-feeding
- Incompatible dietary requirements with the study, food allergies or intolerance to any of the foods in study menus
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 |
|---|---|---|
| Low-oxalate diet and glycolate dosingLow-oxalate diet 4 days of fixed eucaloric diet with low oxalate (<60 mg/day), normal calcium content (600-1000 mg/day) | Dietary supplement | Healthy non-kidney stone forming individuals, Idiopathic Calcium Oxalate Kidney Stone Patients |
| Oral glycolate dosingOral 13C-glycolate dosing (0.5 mg/kg) | Dietary supplement | Healthy non-kidney stone forming individuals, Idiopathic Calcium Oxalate Kidney Stone Patients |
| Oral 13C- ascorbic acid dosingOral 13C- ascorbic acid dosing (0.75 mg/kg) | Dietary supplement | Healthy non-kidney stone forming individuals, Idiopathic Calcium Oxalate Kidney Stone Patients |
Primary outcome
Estimated endogenous oxalate synthesis (oxalate mg/day)
Time frame: 1 day
Basal rate of endogenous oxalate synthesis estimated by repeat fasted hourly urine collections (mg/day)
2 secondary outcomes
24-hour urinary oxalate excretion on low oxalate diet
Time frame: 2 days
contribution of ascorbic acid breakdown to urinary oxalate excretion
Time frame: 2 days
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 27 Aug 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.
Sonia Fargue, PhD principal investigator
University of Alabama at Birmingham
2 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Low-oxalate diet and glycolate dosing, Oral glycolate dosing and Oral 13C- ascorbic acid dosing in people with Kidney Stones and Kidney Calculi, run by University of Alabama at Birmingham at 2 sites 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 6 inclusion and 9 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: looking for participants now, as of the sponsor's last update on 27 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 2 sites 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?
Contact Sonia Fargue, PhD (205-975-6932, sfargue@uabmc.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Estimated endogenous oxalate synthesis (oxalate mg/day) (time frame: 1 day). 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 27 Aug 2026.