Oxalate Formation From Ascorbic Acid

NCT04603898 | Active Not Recruiting DMC

• 2 other identifiers: IRB-300005614R01DK126774
• Study Type: interventional
• Target: 90
• Locations: 1 country
• Sites: 1

Brief Summary

The purpose of this basic research study is to determine the contribution of endogenous ascorbic acid (AA) turnover to urinary oxalate excretion in both normal BMI and obese adult non-stone formers and calcium oxalate stone formers. The studies proposed will use diets of known nutrient composition, a stable isotope of ascorbic acid (13C6-AA) and mass spectrometric techniques to quantify ascorbic acid turnover to oxalate.

Conditions

Kidney Stone

Keywords

Oxalate; Calcium oxalate stones; Ascorbic Acid

Outcome Measures

Primary Outcomes (1)

• Percent contribution of ascorbic acid (AA) to urinary oxalate excretion

  On the last day (Day 4) of controlled diet and 24 hours following ingestion of an oral load of carbon-13 AA (1mg/kg), urine and blood will be collected and the levels of carbon 12 and carbon 13 AA and oxalate measured to determine the percent contribution of AA metabolism to urinary oxalate excretion for each subject.

  Day 4

Study Arms (1)

Controlled Dietary Study

EXPERIMENTAL

Subjects will consume a controlled diet (low in oxalate and ascorbic acid) for six days. After two days of equilibration, subjects will provide a blood sample and ingest an oral load of ascorbic acid (1 mg/kg) with breakfast on Day 3. The following day (Day 4), serial blood and urine collections will occur. On Days 5 through 7, subjects will complete a 24-hr urine collection and blood draw.

Dietary Supplement: Low Oxalate Diet; Dietary Supplement: Carbon-13 Ascorbic Acid Oral Load

Interventions

Low Oxalate Diet DIETARY_SUPPLEMENT

Subjects will be instructed to ingest a controlled diet low in oxalate for a total of 4 days

Controlled Dietary Study

Carbon-13 Ascorbic Acid Oral Load DIETARY_SUPPLEMENT

Subjects will be instructed to ingest 1mg/kg of carbon-13 ascorbic acid at breakfast, 2 days after initiating the low oxalate controlled diet.

Controlled Dietary Study

Eligibility Criteria

• Age: 19 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Able to provide informed consent
• For stone formers: composition of most recent stone \> 50% calcium oxalate, no uric acid component
• For stone formers: first time or recurrent calcium oxalate stone former with stone event within the prior 3 years
• Two 24-hour urine collections with urinary 24-hour creatinine excretion within 20% of appropriate ratio of creatinine (mg) / body weigh (kg) for gender
• Willingness to stop supplements (vitamins, Calcium (citrate or carbonate) and other minerals, herbal supplements, nutritional aids, probiotics) for 2 weeks before start and during study
• Willingness to not undertake vigorous exercise during the study
• Normal fasting blood Comprehensive Metabolic Panel (CMP)
• Willingness to ingest menus prepared in Clinical Research Unit at University of Alabama at Birmingham
• No food allergies or intolerance to any of the foods in study menus
• If on medications for stone prevention (e.g. thiazides, citrate supplementation excluding calcium citrate), they should have been on a stable dose regimen for at least 8 weeks prior to and during screening, with no changes in dosing anticipated during study protocol. If on allopurinol for stone prevention, stop it for 2 weeks prior to screening and this will not be administered during the study as it has anti-oxidant properties.

You may not qualify if:

• Diabetes
• Gout
• Hypertension
• Estimated Glomerular Filtration Rate (eGFR) less than 60ml/min/1.73m2
• Primary hyperoxaluria
• Nephrotic syndrome
• Enteric hyperoxaluria
• Renal tubular acidosis
• Primary hyperparathyroidism
• Liver disease
• Auto-immune disorder
• Neurogenic bladder
• Urinary diversion
• Bariatric surgery
• Active malignancy or treatment for malignancy within 12 months prior to screening

Sponsors & Collaborators

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

Study Sites (1)

University of Alabama at Birmingham

Birmingham, Alabama, 35243-3353, 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

• John Knight, PhD

  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: October 21, 2020
• First Posted: October 27, 2020
• Study Start: November 15, 2021
• Primary Completion (Estimated): December 1, 2026
• Study Completion (Estimated): February 1, 2027
• Last Updated: June 9, 2026

Record last verified: 2026-06

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)