Gut Oxalate Absorption in Calcium Oxalate Stone Disease
- Conditions
- Kidney CalculiHealthyUrolithiasisUrolithiasis, Calcium OxalateNephrolithiasisNephrolithiasis, Calcium OxalateKidney StoneOxalate UrolithiasisOxaluria
- Interventions
- Dietary Supplement: Low-oxalate dietDietary Supplement: High-oxalate dietOther: soluble oxalate gut absorption test
- Registration Number
- NCT06331546
- Lead Sponsor
- University of Alabama at Birmingham
- 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
- Detailed Description
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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Recruitment & Eligibility
- Status
- RECRUITING
- Sex
- All
- Target Recruitment
- 80
- 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%
- 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
- Study Type
- INTERVENTIONAL
- Study Design
- PARALLEL
- Arm && Interventions
Group Intervention Description Healthy non-kidney stone forming individuals High-oxalate diet Low and High oxalate fixed diets. Soluble oxalate absorption test. Idiopathic Calcium Oxalate Kidney Stone Patients Low-oxalate diet Low and High oxalate fixed diets. Soluble oxalate absorption test. Healthy non-kidney stone forming individuals soluble oxalate gut absorption test Low and High oxalate fixed diets. Soluble oxalate absorption test. Idiopathic Calcium Oxalate Kidney Stone Patients soluble oxalate gut absorption test Low and High oxalate fixed diets. Soluble oxalate absorption test. Healthy non-kidney stone forming individuals Low-oxalate diet Low and High oxalate fixed diets. Soluble oxalate absorption test. Idiopathic Calcium Oxalate Kidney Stone Patients High-oxalate diet Low and High oxalate fixed diets. Soluble oxalate absorption test.
- Primary Outcome Measures
Name Time Method Net Gastrointestinal absorption of food-bound oxalate 4 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 (%)
- Secondary Outcome Measures
Name Time Method Absorption of soluble 13C2-oxalate 1 day Proportion of 13C2-oxalate recovered in urine to the amount orally ingested (%)
Estimated endogenous oxalate synthesis (oxalate mg/day) 2 days 24-hour urinary oxalate excretion on the low oxalate diet (mg/day)
Trial Locations
- Locations (2)
University of Alabama at Birmingham
🇺🇸Birmingham, Alabama, United States
UTSW
🇺🇸Dallas, Texas, United States