GI Oxalate Absorption

NCT05356000 | Recruiting

• 1 other identifier: IRB22-0023
• Study Type: interventional
• Target: 30
• Locations: 1 country
• Sites: 1

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

Keywords

Roux-en-Y Gastric Bypass; RYGB; Oxalate

Outcome Measures

Primary Outcomes (6)

• 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)

  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)

  6 days

• Percent absorption of 13C2-oxalate from pre-load baseline (time 0) to 2, 4-, 6-, and 24-hour time points

  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.

  6 days

• Change in urine 13C2-oxalate from pre-load baseline (time 0) to 2, 4-, 6-, and 24-hour time points

  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.

  6 days

• Percent absorption total urine oxalate from pre-load baseline (time 0) to 2, 4-, 6-, and 24-hour time points

  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.

  6 days

• Percent absorption of sucralose from pre-load baseline (time 0) to 2, 4-, 6-, and 24-hour time points

  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.

  6 days

• Change in urine sucralose from pre-load baseline (time 0) to 2, 4-, 6-, and 24-hour time points

  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.

  6 days

Secondary Outcomes (1)

• Compare change in urine oxalate levels from baseline to post-low oxalate diet between the three groups: lean kidney stone patients, obese kidney stone patients, and post- Roux-en-Y gastric bypass kidney stone patients

  6 days

Study Arms (1)

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

OTHER

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

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

Interventions

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

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.

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

Eligibility Criteria

• Age: 18 Years - 70 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• 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

You may not qualify if:

• 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

Sponsors & Collaborators

• University of Chicago: lead
• University of Alabama at Birmingham: collaborator

Study Sites (1)

University of Chicago Medical Center

Chicago, Illinois, 60637, United States

RECRUITING

MeSH Terms

Conditions

Kidney Calculi

Condition Hierarchy (Ancestors)

Nephrolithiasis; Kidney Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Urogenital Diseases; Urolithiasis; Urinary Calculi; Male Urogenital Diseases; Calculi; Pathological Conditions, Anatomical; Pathological Conditions, Signs and Symptoms

Central Study Contacts

Megan Prochaska, MD

CONTACT

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

Elaine Worcester, MD

CONTACT

773-702-3630; eworcest@medicine.bsd.uchicago.edu

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: PREVENTION
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: April 26, 2022
• First Posted: May 2, 2022
• Study Start: January 25, 2023
• Primary Completion (Estimated): June 2, 2026
• Study Completion (Estimated): August 2, 2026
• Last Updated: August 19, 2025

Record last verified: 2025-08

Locations

US (1)