Investigating how the gut absorbs oxalate in kidney stone patients

Gastrointestinal Oxalate Absorption in Calcium Oxalate Stone Disease

Not applicable Interventional University of Alabama at Birmingham · NCT06331546

This study is trying to see if people with kidney stones absorb more oxalate from their diet than healthy individuals, which might lead to more oxalate in their urine.

Quick facts

PhaseNot applicable
Study typeInterventional
Enrollment80 (estimated)
Ages18 Years to 70 Years
SexAll
SponsorUniversity of Alabama at Birmingham Academic / other
Locations2 sites (Birmingham, Alabama and 1 other locations)
Trial IDNCT06331546 on ClinicalTrials.gov

What this trial studies

This clinical trial aims to determine if patients with idiopathic calcium oxalate kidney stones absorb more dietary oxalate, leading to increased urinary oxalate excretion. The study will recruit both kidney stone patients and healthy volunteers, who will follow controlled low and high oxalate diets for five days. Participants will undergo a 13C2-oxalate absorption test to measure gut permeability, with urine, blood, stool, and breath samples collected throughout the study. The goal is to better understand the relationship between dietary oxalate absorption and kidney stone formation.

Who should consider this trial

Good fit: Ideal candidates include adults aged 18-70 with a history of calcium oxalate kidney stones.

Not a fit: Patients with chronic kidney disease, primary hyperoxaluria, or other significant renal or metabolic disorders may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could lead to improved dietary recommendations for preventing calcium oxalate kidney stones.

How similar studies have performed: While there have been studies on dietary oxalate and kidney stones, this specific approach to measuring gut absorption is relatively novel.

Eligibility criteria

Show full inclusion / exclusion criteria
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

Where this trial is running

Birmingham, Alabama and 1 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Kidney StoneKidney CalculiUrolithiasisUrolithiasis, Calcium OxalateNephrolithiasisNephrolithiasis, Calcium OxalateOxalate UrolithiasisOxaluria
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.