Influence of Obesity on Oxalate Metabolism and Handling in Calcium Oxalate Stone Formers

Study Overview
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Brief Summary
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The primary goals of this study are to determine the contribution of dietary oxalate absorption, renal oxalate handling, and endogenous oxalate synthesis to urinary oxalate excretion in normal Body Mass Index (BMI) and obese calcium oxalate kidney stone formers.

Official Title
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Influence of Obesity on Oxalate Metabolism and Handling in Calcium Oxalate Stone Formers

Conditions
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Kidney Stone

Intervention / Treatment
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* Other: Controlled Diet
* Dietary Supplement: Carbon-13 Oxalate and Sucralose Ingestion


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Normal Body Mass Index (≥ 18.5 to < 25); Obese Body Mass Index (≥ 30 to ≤ 45) Able to provide informed consent Willingness to consume controlled diet Composition of most recent stone > 50% calcium oxalate, no uric acid component First time or recurrent calcium oxalate stone former 24-hour urine collections with creatinine values within 20% of appropriate ratio of creatinine (mg)/body weight (kg) for gender, and with creatinine values that are consistent between collections (within 20% of each other) Willingness to stop supplements [vitamins, Ca (citrate or carbonate) and other minerals, herbal supplements, nutritional aids, probiotics] for 14 days before start and during study Willingness to not undertake vigorous exercise during the controlled dietary study Normal fasting blood Comprehensive Metabolic Panel Hemoglobin A1c < 6.5% No food allergies or intolerance to any of the food in study menus Permitted/willing to discontinue medications for kidney stone prevention, including thiazides, allopurinol, and febuxostat and citrate preparations, for 14 days before start and during the studies. They will be instructed to restart these medications at the conclusion of the study Exclusion Criteria: Diabetes Abnormal fasting comprehensive metabolic panel (CMP) Hemoglobin A1c (HbA1c) result ≥ 6.5% Gout Estimated Glomerular Filtration Rate (eGFR) <60 ml/min/1.73m^2 Primary hyperoxaluria Cystic fibrosis Cystinuria Uric acid stone former Utilization of immunosuppressive medication Nephrotic syndrome Enteric hyperoxaluria Gastrointestinal disorder that could impact oxalate transport Sarcoidosis Uncontrolled hypertension Renal tubular acidosis Primary hyperparathyroidism Liver disease Neurogenic bladder Urinary diversion Chronic diarrhea Bariatric surgery Active malignancy or treatment for malignancy within 12 months prior to screening Pregnancy Breast feeding/nursing Females of child bearing age who are not able to use an effective method of birth control during the study Mental/medical condition that is likely to impede successful study completion Illness including flu / common cold / fever 14 days before study and during study Diarrhea or other abnormal gastrointestinal event (e.g. abnormal bowel movements) 14 days before study or during study Antibiotic use within last 6 months (based on recommendations of the NIH Human Microbiome Project, Protocol A) Inability or unwillingness to undergo MRI

Ages Eligible for Study
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Minimum Age: 19 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Controlled Dietary Study<br>Participants will consume the controlled diet for five days. After one day on the diet, subjects will provide three 24-hour urine collections. On the last dayof the diet, subjects will come in a fasted state to ingest a small amount of carbon-13 oxalate and sucralose, with hourly urine collections and blood samples being taken before and after the ingestion. | Other: Controlled Diet<br>* Participant will consume a controlled low oxalate diet for five days<br>Dietary Supplement: Carbon-13 Oxalate and Sucralose Ingestion<br>* Subjects will ingest a small amount of carbon-13 oxalate and sucralose, dissolved in water.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Urinary Oxalate Excretion | Urinary oxalate excretion from urine samples will be measured as mg/day | Baseline through Day 5 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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oxalate, kidney stone