NCT04590690 · University of Chicago
Gut Microbiome and Sex as Risk Factors for Kidney Stones After Bariatric Surgery
What this study is about
This is a single-center study that aims to better understand how diet and sex affect the risk of kidney stones in people who have had gastric bypass surgery. Subjects will be asked to follow a special (clinic-provided) diet for six days and come to a research clinic for 3 study visits.
View original scientific description
This is a single-center study that aims to better understand how diet and sex affect the risk of kidney stones in people who have had gastric bypass surgery. Subjects will be asked to follow a special (clinic-provided) diet for six days and come to a research clinic for 3 study visits.
Interventions
OTHER
Special diet
The research clinic will provide subjects with a special diet for six days. After six days of isocaloric sodium, calcium and fluid intake, the study team will analyze three sequential 24-hour urine compositions including supersaturation of calcium oxalate, calcium, and urine volume, as well as stool collections. We will also evaluate components of 24-hour urine composition, specifically supersaturation, and the microbial contributions to urinary composition in 72-hour stool samples simultaneously collected using shot-gun metagenomic sequencing in men and women 1 year after surgery.
Primary outcome measures
Change in urine calcium oxalate supersaturation over time
Time frame: Multiple times over approximately 13 months
Calculated using EQUIL2 from the measured urine calcium, citrate, oxalate, and volume that are directly measured in the urine
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
- Participants without history of stone disease, family history of stone disease
- Participants pre-bariatric surgery who are approved and planned for surgery in the Bariatric Surgery Center at University of Chicago Medicine.
Exclusion criteria
- Patients with primary renal diseases or renal impairment (eGFR \< 90)
- Patients with known bladder voiding problems
- Patients with 25-vitamine D deficiency, as defined by level \< 25ng/mL
Where
- Chicago, Illinois
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 May 11, 2026 · Source of record for eligibility and locations