Gut Oxalate Absorption in Calcium Oxalate Stone Disease

This study is looking into whether people with calcium oxalate kidney stones absorb more oxalate from their food, which could lead to more oxalate in their urine. Researchers will compare adults aged 18-70 with a history of calcium oxalate kidney stones to healthy volunteers without stones. You would follow special diets, including a low-oxalate diet (less than 60 mg/day) and a moderately high-oxalate diet (250-300 mg/day), each for 4 days. You would also take a special soluble oxalate gut absorption test. The main goal is to measure how much food-bound oxalate is absorbed by your digestive system.

Study design: This interventional study plans to enroll 80 participants, including 40 with kidney stones and 40 without, matched for age and gender.
What's involved: You would follow fixed diets for 5 days at a time, ingest a soluble oxalate and sugar preparation, and provide urine, blood, stool, and breath samples. You would also need to stop certain supplements for two weeks before and during the study.
Compensation: Not stated in the trial record.
Follow-up: The primary endpoint, net gastrointestinal absorption of food-bound oxalate, is measured at 4 days.

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Gut Oxalate Absorption in Calcium Oxalate Stone Disease

Recruiting

NAAges 18–70InterventionalBasic science

University of Alabama at Birmingham

~80 participants

Updated 2026-08-27 on ClinicalTrials.gov

What's tested:Low-oxalate dietHigh-oxalate dietsoluble oxalate gut absorption test

At a glance

Recruiting sites

2 of 2 listed sites are recruiting right now

RecruitingSuspended, closed, or not yet open

What they're measuring

Net Gastrointestinal absorption of food-bound oxalate

Measured over 4 day

Conditions

Kidney Stone

Kidney Calculi

Urolithiasis

Urolithiasis, Calcium Oxalate

Nephrolithiasis

Nephrolithiasis, Calcium Oxalate

Oxalate Urolithiasis

Oxaluria

Healthy

Where it's being run

2 sites across 2 states

Alabama1

Texas1

Study leadership

Sonia Fargue, PhD · PRINCIPAL_INVESTIGATOR · University of Alabama at Birmingham

Who to contact

Sonia Fargue, PhD

[email protected]

2059756932

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Do you actually qualify for this trial?

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Eligibility criteria

Inclusion

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

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

What this trial measures

Net Gastrointestinal absorption of food-bound oxalate4 day
difference between 24-hour urinary oxalate excretion on the high oxalate diet and the low oxalate diet, normalized to the difference in dietary oxalate composition of the two diets (%)

Trialytics