Recruiting

Oxalate Absorption

Sponsor:

University of Alabama at Birmingham

Code:

NCT06331546

Conditions

Kidney Stone

Kidney Calculi

Urolithiasis

Urolithiasis, Calcium Oxalate

Nephrolithiasis

Eligibility Criteria

Sex: All

Age: 18 - 70+

Healthy Volunteers: Accepted

Interventions

Low-oxalate diet

High-oxalate diet

soluble oxalate gut absorption test

Study Details

Brief summary:

The goal of this clinical trial study is to test if patients with idiopathic calcium oxalate kidney stones have an increased absorption of dietary oxalate, which would lead to increased urinary excretion of oxalate.

The study will recruit adult patients with a history of calcium oxalate kidney stones and healthy volunteers without kidney stones.

Participants will

  • ingest fixed diets containing low and moderately high amounts of oxalate for 5 days at a time
  • ingest a soluble form of oxalate and sugar preparations to test gut permeability
  • collect urine, blood, stool and breath sample during the fixed diets and the soluble oxalate test

Conditions

Kidney Stone

Kidney Calculi

Urolithiasis

Urolithiasis, Calcium Oxalate

Nephrolithiasis

Study ID

NCT06331546

Start date

Apr 17, 2024

Status verified date

Oct, 2026

Completion date

Dec 31, 2031

Anticipated

Primary completion date

Dec 31, 2030

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18 - 70+

Healthy Volunteers: Accepted

Inclusion Criteria:

  • age 18-80 yrs
  • Body Mass Index > 18.5 kg/m2
  • Normal fasting serum electrolytes on comprehensive metabolic profile
  • Willing to ingest fixed diets
  • Willing to stop supplements (vitamins including vitamin C, calcium (citrate or carbonate) and other minerals, herbal supplements, nutritional aids, probiotics) for 2 weeks before start and during study.
  • For stone formers: first time or recurrent Calcium Oxalate stone former. Composition of most recent stone ≥ 50% calcium oxalate if available, uric acid component <20%

Exclusion Criteria:

  • Chronic Kidney Disease stage 4-5
  • Primary hyperoxaluria, Enteric (secondary) hyperoxaluria
  • Liver, bowel, endocrine or renal diseases (other than idiopathic Calcium Oxalate kidney stones) or any other condition that may influence the absorption, transport or urinary excretion of ions, which will compromise the interpretation of results, including: Cystic fibrosis, Celiac disease, Cystinuria, Uric acid stone former, Nephrotic syndrome, Sarcoidosis, Renal tubular acidosis, Primary hyperparathyroidism, Neurogenic bladder, Urinary diversion, Chronic diarrhea, Bariatric surgery, Inflammatory bowel disease
  • Pregnancy or breast-feeding
  • Incompatible dietary requirements with the study, food allergies or intolerance to any of the foods in study menus
  • Active malignancy or treatment for malignancy within 12 months prior to screening
  • Utilization of immunosuppressive medication
  • Uncontrolled hypertension or diabetes
  • Diabetes type 1
  • Chronic NSAID use

Study Design

Enrollment

80 participants

Anticipated

Allocation

Non randomized

Intervention Model

Parallel Assignment

Primary purpose

Basic Science

Interventions and Outcome Measures

Arms

experimental: Idiopathic Calcium Oxalate Kidney Stone Patients

Low and High oxalate fixed diets. Soluble oxalate absorption test.

active comparator: Healthy non-kidney stone forming individuals

Low and High oxalate fixed diets. Soluble oxalate absorption test.

Interventions

Low-oxalate diet

4 days of fixed eucaloric diet with low oxalate (<60 mg/day), normal calcium content (600-1000 mg/day)

High-oxalate diet

4 days of fixed eucaloric diet with moderately high oxalate (250-300 mg/day), normal calcium content (600-1000 mg/day)

soluble oxalate gut absorption test

Oral ingestion of 13C2-oxalate and sucralose.

Primary outcome measure

  • Net Gastrointestinal absorption of food-bound oxalate [ Time Frame: 4 day ]

Central Contacts and Locations

Central contacts

Sonia Fargue, PhD

2059756932sfargue@uabmc.edu

Locations

University of Alabama at Birmingham

Recruiting

Birmingham, Alabama, United States, 35294

Contacts

Sonia Fargue, PhD

205-9756932kidneystone@uabmc.edu

Research Coordinator

205-9345712kidneystone@uabmc.edu

Principal Investigator:

Sonia Fargue, PhD

UTSW

Recruiting

Dallas, Texas, United States, 75390

Contacts

Naim Maalouf, MD

Naim.Maalouf@UTSouthwestern.edu

Peter Gales

Peter.Gales@UTSouthwestern.edu

Principal Investigator:

Naim Maalouf, MD

More Information

Sponsor

University of Alabama at Birmingham

Last update posted

Oct 13, 2026

Last verified

Oct, 2026

Trial information was received from ClinicalTrials.gov and was last updated on 2026-10-24. This information was provided to ClinicalTrials.gov by University of Alabama at Birmingham on 2026-10-13. Recruitment status is synced daily from ClinicalTrials.gov and may not reflect the sponsor's current status. Confirm during your call.