Recruiting

Observational Study

Sponsor:

University of Chicago

Code:

NCT04590690

Conditions

Bariatric Surgery Candidate

Eligibility Criteria

Sex: All

Age: 18 - 70+

Healthy Volunteers: Not accepted

Interventions

Special diet

Study Details

Brief summary:

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.

Conditions

Bariatric Surgery Candidate

Study ID

NCT04590690

Start date

Nov 1, 2020

Status verified date

May, 2026

Completion date

May 1, 2027

Anticipated

Primary completion date

Mar 1, 2027

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18 - 70+

Healthy Volunteers: Not accepted

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

Study Design

Enrollment

28 participants

Anticipated

Intervention Model

Single group

Primary purpose

Prevention

Interventions and Outcome Measures

Arms

experimental: Roux-en-y gastric bypass subjects

Inclusion Criteria: Age 18-70. Participants pre-Roux-en-y gastric bypass (RYGB) who are approved and planned for Roux-en-y gastric bypass surgery in the Bariatric Surgery Center at the UCM.

Exclusion Criteria: Patients with primary kidney diseases, kidney stone disease, or kidney impairment (eGFR < 90). Patients with known bladder voiding problems.

Participants will complete a diet record and a 24-hour urine collection both before and after surgery.

Participants will consume a 3 day fixed diet and present to the clinical research center for timed blood and urine draws. They will do this before and twice after (1 month and 1 year) surgery.

experimental: Sleeve gastrectomy subjects

Inclusion Criteria: Age 18-70. Participants pre-sleeve gastrectomy who are approved and sleeve gastrectomy in the Bariatric Surgery Center at the UCM.

Exclusion Criteria: Patients with primary kidney diseases, kidney stone disease, or kidney impairment (eGFR < 90). Patients with known bladder voiding problems.

Participants will complete a diet record and a 24-hour urine collection both before and after surgery.

Participants will consume a 3 day fixed diet and present to the clinical research center for timed blood and urine draws. They will do this before and twice after (1 month and 1 year) surgery.

Interventions

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 measure

  • Change in urine calcium oxalate supersaturation over time [ Time Frame: Multiple times over approximately 13 months ]

Central Contacts and Locations

Central contacts

Megan Prochaska

(773) 702-1000mprocha2@medicine.bsd.uchicago.edu

Prochaska Megan, MD

(773) 702-1000mprocha2@medicine.bsd.uchicago.edu

Locations

University of Chicago Medical Center

Recruiting

Chicago, Illinois, United States, 60637

Contacts

Megan Prochaska, MD

773-702-1000mprocha2@medicine.bsd.uchicago.edu

More Information

Sponsor

University of Chicago

Last update posted

May 11, 2026

Last verified

May, 2026

Keywords

  • bariatric surgery
  • kidney stones

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-09. This information was provided to ClinicalTrials.gov by University of Chicago on 2026-05-11.