Gut Oxalate Absorption in Calcium Oxalate Stone Disease

NCT ID: NCT06331546

Last Updated: 2025-05-13

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

RECRUITING

Clinical Phase

NA

Total Enrollment

80 participants

Study Classification

INTERVENTIONAL

Study Start Date

2024-04-17

Study Completion Date

2031-12-31

Brief Summary

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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

Detailed Description

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In this study the investigators propose to measure the net gastrointestinal absorption of oxalate both by food-bound oxalate, using low- (\<60 mg/day) and high- (250-300 mg/day) oxalate diets (600-800 mg daily calcium in both), and by the soluble 13C2-oxalate oral test in both Calcium Oxalate Kidney Stone patients and matched controls.

Phase 1. Screening and low-oxalate diet 24-hr urinary excretions. Between the University of Alabama at Birmingham (UAB) and the University of Texas Southwestern Medical Center (UTSW), the study will enroll 40 subjects with idiopathic Calcium Oxalate Kidney Stone (20 Males/20 Females) and 40 non-kidney stone forming controls (20 Males/20 Females). Participants in the two groups will be matched for age (within 10 yrs) and gender. Screening will include blood complete metabolic profile and two 24-hr urine specimens collected at home on self-choice diets and anthropometric measurements.

Participants will then ingest the controlled low-oxalate (\<60 mg/d) diet for 5 consecutive days and collect two 24-hr urines after 2 days of dietary equilibration.

Phase 2. 13C2-Oxalate gut absorption tests. On Day 5, participants will arrive after an overnight fast in the research unit to undergo the 13C2-oxalate absorption test. After a 1-hour baseline urine collection, they will ingest an oral load containing 100 mg 13C2-oxalate and 1 g sucralose, dissolved in bottled water. For the next 9 hrs, blood and urine will be collected hourly, and breath as more time points. They will remain on the fixed diet for 24 hrs with a breakfast 2 hours after the load, lunch 6 hrs post-load, and dinner at home 12 hrs post-load. They will collect the remainder of their 24-hr urine at home and the totality of the stool eliminated during the first 24 hrs after the load using kits provided.

Phase 3. High-oxalate diet 24-hr urinary excretions. After a minimum of 1 week wash-out period, during which participants will eat freely, participants will consume the high oxalate (250-300 mg/day) diet for the next 4 days. Two 24-hr urine specimens will be collected after 2 days of equilibration and a fasting blood draw on the morning of Day 5.

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Conditions

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Kidney Stone Kidney Calculi Urolithiasis Urolithiasis, Calcium Oxalate Nephrolithiasis Nephrolithiasis, Calcium Oxalate Oxalate Urolithiasis Oxaluria Healthy

Study Design

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Allocation Method

NON_RANDOMIZED

Intervention Model

PARALLEL

Primary Study Purpose

BASIC_SCIENCE

Blinding Strategy

NONE

Study Groups

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Idiopathic Calcium Oxalate Kidney Stone Patients

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

Group Type EXPERIMENTAL

Low-oxalate diet

Intervention Type DIETARY_SUPPLEMENT

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

High-oxalate diet

Intervention Type DIETARY_SUPPLEMENT

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

Intervention Type OTHER

Oral ingestion of 13C2-oxalate and sucralose.

Healthy non-kidney stone forming individuals

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

Group Type ACTIVE_COMPARATOR

Low-oxalate diet

Intervention Type DIETARY_SUPPLEMENT

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

High-oxalate diet

Intervention Type DIETARY_SUPPLEMENT

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

Intervention Type OTHER

Oral ingestion of 13C2-oxalate and sucralose.

Interventions

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Low-oxalate diet

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

Intervention Type DIETARY_SUPPLEMENT

High-oxalate diet

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

Intervention Type DIETARY_SUPPLEMENT

soluble oxalate gut absorption test

Oral ingestion of 13C2-oxalate and sucralose.

Intervention Type OTHER

Eligibility Criteria

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Inclusion Criteria

* age 18-70 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
Minimum Eligible Age

18 Years

Maximum Eligible Age

70 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

Yes

Sponsors

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University of Texas Southwestern Medical Center

OTHER

Sponsor Role collaborator

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

NIH

Sponsor Role collaborator

University of Alabama at Birmingham

OTHER

Sponsor Role lead

Responsible Party

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Sonia Fargue

Assistant Professor

Responsibility Role PRINCIPAL_INVESTIGATOR

Principal Investigators

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Sonia Fargue, PhD

Role: PRINCIPAL_INVESTIGATOR

University of Alabama at Birmingham

Locations

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University of Alabama at Birmingham

Birmingham, Alabama, United States

Site Status RECRUITING

UTSW

Dallas, Texas, United States

Site Status ACTIVE_NOT_RECRUITING

Countries

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United States

Central Contacts

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Sonia Fargue, PhD

Role: CONTACT

2059756932

Facility Contacts

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Sonia Fargue, PhD

Role: primary

205-975-6932

Research Coordinator

Role: backup

205-9345712

Other Identifiers

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R01DK137784

Identifier Type: NIH

Identifier Source: secondary_id

View Link

IRB300004693-GIA

Identifier Type: -

Identifier Source: org_study_id

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