NCT05356000 · University of Chicago
GI Oxalate Absorption
What this study is about
This study aims to learn more about how oxalate, a compound found in many foods, may affect a person's chances of forming kidney stones. Active participation in this study will last for around one week. For the first two days, subjects will be asked to eat a special diet at home. From Days 3-5, they will eat special meals delivered to their home from a research clinic at the University of Chicago.
View original scientific description
This study aims to learn more about how oxalate, a compound found in many foods, may affect a person's chances of forming kidney stones. Active participation in this study will last for around one week. For the first two days, subjects will be asked to eat a special diet at home. From Days 3-5, they will eat special meals delivered to their home from a research clinic at the University of Chicago. They will also collect 24-hour urine samples at home on Days 4 and 5. On Day 6, they will come in to the research clinic at the University of Chicago in Hyde Park, where they will spend most of the day. They will receive a special liquid that contains oxalate, and we will have them eat a specially prepared breakfast that is low in oxalate and citrate.
Interventions
OTHER
Special low-oxalate diet followed by all-day visit to University of Chicago research clinic
Active participation in this study will last for around one week. For the first two days, participants will be asked to eat a special diet at home. From Days 3-5, they will eat special meals that will be delivered to their home from a research clinic at the University of Chicago. They will also collect urine at home on Days 4 and 5. On Day 6, subjects will come in to the research clinic at the University of Chicago in Hyde Park, where they will spend most of the day. They will receive a special liquid that contains oxalate, and will receive a specially prepared breakfast that is low in oxalate and citrate. After this, we will collect their urine and blood throughout the day. We will draw blood 4 separate times.
Primary outcome measures
Change in 24-hour urine oxalate from baseline to after 5 days on low oxalate diet (2 days on participant managed, 3 days on clinical research center prepared diet of 50mg/day)
Time frame: 6 days
24-hour urine oxalate will be measured before and after participants follow a low oxalate diet for 5 total days (3 days will be clinical research center prepared food with known measured oxalate content of 50mg/day)
Percent absorption of 13C2-oxalate from pre-load baseline (time 0) to 2, 4-, 6-, and 24-hour time points
Time frame: 6 days
Will be measured or calculated at time points 0, 2-hours, 4-hours, 6-hours and 24-hours after sodium 13C2-oxalate and sucralose consumption. We will compare change in urine total urine oxalate and 13C2-oxalate/total oxalate and sucralose each time period for all participants.
Change in urine 13C2-oxalate from pre-load baseline (time 0) to 2, 4-, 6-, and 24-hour time points
Time frame: 6 days
Will be measured or calculated at time points 0, 2-hours, 4-hours, 6-hours and 24-hours after sodium 13C2-oxalate and sucralose consumption. We will compare change in urine total urine oxalate and 13C2-oxalate/total oxalate and sucralose each time period for all participants.
Percent absorption total urine oxalate from pre-load baseline (time 0) to 2, 4-, 6-, and 24-hour time points
Time frame: 6 days
Will be measured or calculated at time points 0, 2-hours, 4-hours, 6-hours and 24-hours after sodium 13C2-oxalate and sucralose consumption. We will compare change in urine total urine oxalate and 13C2-oxalate/total oxalate and sucralose each time period for all participants.
Percent absorption of sucralose from pre-load baseline (time 0) to 2, 4-, 6-, and 24-hour time points
Time frame: 6 days
Will be measured or calculated at time points 0, 2-hours, 4-hours, 6-hours and 24-hours after sodium 13C2-oxalate and sucralose consumption. We will compare change in urine total urine oxalate and 13C2-oxalate/total oxalate and sucralose each time period for all participants.
Change in urine sucralose from pre-load baseline (time 0) to 2, 4-, 6-, and 24-hour time points
Time frame: 6 days
Will be measured or calculated at time points 0, 2-hours, 4-hours, 6-hours and 24-hours after sodium 13C2-oxalate and sucralose consumption. We will compare change in urine total urine oxalate and 13C2-oxalate/total oxalate and sucralose each time period for all participants.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Post-Roux-en-Y gastric bypass stone formers:
- Previous history of Roux-en-Y gastric bypass
- History of at least one calcium-based kidney stone after surgery
- Pre-protocol urine oxalate above the lab normal range (50mg/day) Obese stone formers:
- Body mass index (BMI) \>=30kg/m2
- History of at least one calcium-based kidney stone
- Pre-protocol urine oxalate above the lab normal range (50mg/day) Non-obese stone formers:
- Age 18-70, BMI between 18.5-29.9 kg/m2
- History of at least one calcium-based kidney stone
Exclusion criteria
- Post-Roux-en-Y gastric bypass stone formers:
- History of colon resection (partial or complete)
- History of duodenal switch bowel surgery
- History of ileal-jejunal bypass surgery
- History of primarily uric acid, cysteine, or struvite stones Obese and non-obese stone formers:
- History of bowel surgery
- History of colon resection
- History of inflammatory bowel disease (Crohn's disease, Ulcerative Colitis)
- History of primarily uric acid, cysteine, or struvite stones
Where
- Chicago, Illinois
Collaborators
University of Alabama at Birmingham
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Aug 19, 2025 · Source of record for eligibility and locations