Recruiting

Observational Study

Sponsor:

University of Chicago

Code:

NCT05356000

Conditions

Bariatric Surgery Candidate

Kidney Stone

Eligibility Criteria

Sex: All

Age: 18 - 70

Healthy Volunteers: Not accepted

Interventions

Special low-oxalate diet followed by all-day visit to University of Chicago research clinic

Study Details

Brief summary:

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.

Conditions

Bariatric Surgery Candidate

Kidney Stone

Study ID

NCT05356000

Start date

Jan 25, 2023

Status verified date

Aug, 2025

Completion date

Aug 2, 2026

Anticipated

Primary completion date

Jun 2, 2026

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18 - 70

Healthy Volunteers: Not accepted

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

Study Design

Enrollment

30 participants

Anticipated

Intervention Model

Single group

Primary purpose

Prevention

Interventions and Outcome Measures

Arms

other: Subjects who will follow low-oxalate diet followed by visit to research clinic

30 stone-forming participants will be recruited to this study.

Interventions

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 measure

  • 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 ]
  • Percent absorption of 13C2-oxalate from pre-load baseline (time 0) to 2, 4-, 6-, and 24-hour time points [ Time Frame: 6 days ]
  • Change in urine 13C2-oxalate from pre-load baseline (time 0) to 2, 4-, 6-, and 24-hour time points [ Time Frame: 6 days ]
  • Percent absorption total urine oxalate from pre-load baseline (time 0) to 2, 4-, 6-, and 24-hour time points [ Time Frame: 6 days ]
  • Percent absorption of sucralose from pre-load baseline (time 0) to 2, 4-, 6-, and 24-hour time points [ Time Frame: 6 days ]
  • Change in urine sucralose from pre-load baseline (time 0) to 2, 4-, 6-, and 24-hour time points [ Time Frame: 6 days ]

Central Contacts and Locations

Central contacts

Megan Prochaska, MD

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

Elaine Worcester, MD

773-702-3630eworcest@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

Principal Investigator:

Megan Prochaska, MD

More Information

Sponsor

University of Chicago

Last update posted

Aug 19, 2025

Last verified

Aug, 2025

Keywords

  • Roux-en-Y Gastric Bypass
  • RYGB
  • Oxalate

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 2025-08-19.