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Gut Oxalate Absorption in Calcium Oxalate Stone Disease

Sponsor: University of Alabama at Birmingham • ClinicalTrials.gov ID: NCT06331546

Registry updated: 2026-10-13

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Description

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

Interventions

Low-oxalate diet (Dietary supplement)
4 days of fixed eucaloric diet with low oxalate (\<60 mg/day), normal calcium content (600-1000 mg/day)
High-oxalate diet (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 (Other)
Oral ingestion of 13C2-oxalate and sucralose.

Eligibility criteria

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

Conditions

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

Locations

University of Alabama at Birmingham — Birmingham, Alabama, United States
UTSW — Dallas, Texas, United States

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Official Source

Data sourced from ClinicalTrials.gov, a service of the U.S. National Institutes of Health.

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