Understanding how oxalate affects kidney stone formation in bariatric surgery candidates

Determine the Contribution of Paracellular GI Oxalate Absorption in Obese and Roux-en-Y Gastric Bypass Kidney Stone Patients

Not applicable Interventional University of Chicago · NCT05356000

This study is testing how a low-oxalate diet affects kidney stone formation in people who are planning to have weight loss surgery and those who already have kidney stones.

Quick facts

PhaseNot applicable
Study typeInterventional
Enrollment30 (estimated)
Ages18 Years to 70 Years
SexAll
SponsorUniversity of Chicago Academic / other
Locations1 site (Chicago, Illinois)
Trial IDNCT05356000 on ClinicalTrials.gov

What this trial studies

This study investigates the relationship between dietary oxalate and the formation of kidney stones in individuals who have undergone Roux-en-Y gastric bypass surgery, as well as in obese and non-obese stone formers. Participants will follow a low-oxalate diet for three days, after which they will undergo a specialized oral load test to measure oxalate absorption. The study aims to collect urine samples to analyze oxalate levels and understand how oxalate is absorbed in the gastrointestinal tract. The research is conducted at the University of Chicago, utilizing their Clinical Research Center.

Who should consider this trial

Good fit: Ideal candidates include adults aged 18-70 who have a history of kidney stones and have undergone Roux-en-Y gastric bypass, as well as obese and non-obese individuals with similar histories.

Not a fit: Patients with a history of certain bowel surgeries or specific types of kidney stones may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could provide insights into dietary modifications that may reduce the risk of kidney stones in at-risk populations.

How similar studies have performed: While the specific approach of this study may be novel, previous studies have indicated a link between dietary oxalate and kidney stone formation, suggesting potential for success.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

Post-Roux-en-Y gastric bypass stone formers:

* Age 18-70
* 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:

* Age 18-70
* 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 this trial is running

Chicago, Illinois

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Bariatric Surgery CandidateKidney StoneRoux-en-Y Gastric BypassRYGBOxalate
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.