Effect of Weight Loss on Urinary Oxalate Excretion in Obese Calcium Oxalate Kidney Stone Formers

NCT04633811 | Active Not Recruiting DMC

• 2 other identifiers: IRB-300006133R01DK128160
• Study Type: interventional
• Target: 14
• Locations: 1 country
• Sites: 1

Brief Summary

This protocol seeks to determine if weight reduction with the Optifast VLCD program leads to reduced contribution of endogenous oxalate synthesis and dietary oxalate absorption to the urinary oxalate pool in obese calcium oxalate stone formers.

Conditions

Kidney Stone

Outcome Measures

Primary Outcomes (1)

• Measurement of 24 hour urinary oxalate excretion

  Subjects will ingest a controlled diet low in oxalate and collect 2 x 24-hour urines before and after the Optifast VLCD Program. The utilization of a low oxalate diet allows assessment of the change in contribution of endogenous oxalate synthesis to the urinary oxalate pool.

  4 days

Study Arms (1)

Controlled Diet and Weight Loss Program

EXPERIMENTAL

Subjects will consume a low oxalate diet with blood and urine collections to establish baseline levels before undergoing a weight loss program with Optifast VLCD products. After completing the weight loss program, subjects will once again consume a low oxalate diet with blood and urine collections to observe any changes that may have occurred due to the weight loss.

Dietary Supplement: Low Oxalate Diet before Weight Loss; Dietary Supplement: Oral load of oxalate and sucralose before Weight Loss; Dietary Supplement: Optifast VLCD Program; Dietary Supplement: Optifast VLCD Transition Phase; Dietary Supplement: Low Oxalate Diet after Weight Loss; Dietary Supplement: Oral load of oxalate and sucralose after Weight Loss

Interventions

Oral load of oxalate and sucralose before Weight Loss DIETARY_SUPPLEMENT

Subjects will ingest 100mg carbon-13 oxalate, and 1 gram of sucralose on day 5 of the 6-day low oxalate diet phase. Following the oral load, blood and urine will be collected every 30 minutes and hourly, respectively

Controlled Diet and Weight Loss Program

Optifast VLCD Program DIETARY_SUPPLEMENT

Subjects will go on a 10-week Intestive level Optifast VLCD weight loss program

Controlled Diet and Weight Loss Program

Low Oxalate Diet after Weight Loss DIETARY_SUPPLEMENT

Subjects will be instructed to ingest a controlled diet low in oxalate for a total of 11 days and collect 2 x 24 hour urines on days 8 and 9

Controlled Diet and Weight Loss Program

Oral load of oxalate and sucralose after Weight Loss DIETARY_SUPPLEMENT

Subjects will ingest 100mg carbon-13 oxalate, and 1 gram of sucralose on day 10 of the 11-day low oxalate diet phase. Following the oral load, blood and urine will be collected every 30 minutes and hourly, respectively

Controlled Diet and Weight Loss Program

Low Oxalate Diet before Weight Loss DIETARY_SUPPLEMENT

Subjects will be instructed to ingest a controlled diet low in oxalate for a total of 6 days. 2 x 24 hour urines will be collected on days 3 and 4.

Controlled Diet and Weight Loss Program

Optifast VLCD Transition Phase DIETARY_SUPPLEMENT

After completion of the 10-week Optifast VLCD Program, subjects will be weaned off the Optifast products for 4 weeks.

Controlled Diet and Weight Loss Program

Eligibility Criteria

• Age: 19 Years - 65 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• First time or recurrent calcium oxalate stone formers defined as composition of most recent stone \>50% calcium oxalate without uric acid component
• Last stone passage or removal greater than 3 months prior to screening
• Body Mass Index (BMI) \>35 kg/m2
• Able to provide consent
• Hemoglobin A1C \<6.5%
• Normal fasting blood CMP: Normal serum Na, K, Cl, CO2, Calcium, Albumin, AST, ALT \<2 times upper limit of normal, Glucose \<126 mg/dl, eGFR \>60 ml/min/1.73 m2.
• hour urine collection with creatinine within 20% of gender appropriate (mg creat/kg body weight) and consistent between collections (within 20% of each other)
• Willing to ingest menus prepared at the University of Alabama and University of Texas Southwestern Clinical Research Units
• Willing to consume the Optifast VLCD diet
• Willing to ingest menus prepared in Metabolic kitchen. No food allergies or intolerance to any of the foods in study menus. Substitutions for lactose intolerance will be made.
• Willing to avoid vigorous exercise during eucaloric, low-oxalate dietary phase
• Willing to stop use of weight-loss medications
• Willing to stop for 14 days before and during study: medications for stone prevention including diuretics, potassium citrate, allopurinol, febuxostat, and calcium, nutritional, or herbal supplements
• Those with controlled hypertension (systolic blood pressure \<160 mmHg, diastolic \<90 mmHg) will be included.
• Those without severe dyslipidemia (LDL \<200 mg/dL, HDL \>30 mg/dL, and triglycerides \<250 mg/dL) will be included. Treated and controlled dyslipidemia is accepted

You may not qualify if:

• Renal colic or past stone surgery in the past 3 months
• Estimated Glomerular Filtration Rate (eGFR) less than 60 ml/min/1.73m2
• History of type 2 diabetes or screening hgb A1c greater than or equal to 6.5%
• Alcohol or drug abuse. Alcohol consumption \>12 units per week and/or unwillingness to abstain from alcohol consumption 2 days before and during the study.
• Mental/medical condition likely to impede study completion
• Current/planned pregnancy or breastfeeding in coming 6 months, unwillingness to use effective method of birth control during the study for individuals of childbearing potential.
• Planned vacation in coming 4 months
• Febrile illness including flu/common cold/COVID-19 within 21 days of study start
• Primary or enteric hyperoxaluria
• Gastrointestinal disorder or surgery that impacts oxalate transport
• Cirrhosis, pancreatic or biliary disorder, porphyria, gout
• Malignancy treated within the past 12 months
• Nephrotic syndrome, neurogenic bladder, urinary diversion
• History of primary hyperparathyroidism, cystinuria, renal tubular acidosis, sarcoidosis, cystic fibrosis
• Uncontrolled hypertension, myocardial infarction in past 6 months, unstable angina, congestive heart failure

Sponsors & Collaborators

• National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK): collaborator
• University of Alabama at Birmingham: lead
• University of Texas Southwestern Medical Center: collaborator

Study Sites (1)

University of Alabama at Birmingham

Birmingham, Alabama, 35243, United States

Location

MeSH Terms

Conditions

Kidney Calculi

Condition Hierarchy (Ancestors)

Nephrolithiasis; Kidney Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Urogenital Diseases; Urolithiasis; Urinary Calculi; Male Urogenital Diseases; Calculi; Pathological Conditions, Anatomical; Pathological Conditions, Signs and Symptoms

Study Officials

• Dean Assimos, MD

  University of Alabama at Birmingham

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal Investigator

Study Record Dates

• First Submitted: November 11, 2020
• First Posted: November 18, 2020
• Study Start: December 3, 2021
• Primary Completion: December 31, 2025
• Study Completion (Estimated): December 31, 2026
• Last Updated: March 6, 2026

Record last verified: 2026-03

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)