Obesity and Endogenous Oxalate Synthesis

The goal of this study is to determine if obesity is associated with increased endogenous oxalate synthesis as assessed by urinary oxalate excretion, which is a known risk factor for calcium oxalate kidney stones.

The study will recruit adult participants without history of kidney stones. Participants will

• Ingest fixed diets containing low amounts of oxalate for 4 days
• Collect 24-hr urine samples during the fixed diet

Study Overview

• Status: Completed
• Conditions: Obesity
• Intervention / Treatment: Dietary supplement: Normal Individuals

Detailed Description

In this study the investigators propose to measure the excretion of urinary oxalate on a fixed diet with controlled amounts of oxalate, in individuals of varying body sizes without history of kidney stones. The 24-hr urinary oxalate excretion on such a low-oxalate normal calcium fixed diet is determined to be an appropriate surrogate for endogenous oxalate synthesis.

Screening phase. The study will enroll 60 individuals without history of kidney stones (30 males/30 females) at the University of Alabama at Birmingham (UAB).

Screening will include blood complete metabolic profile, 24-hr urine specimens collected at home on self-selected diets and anthropometric measurements.

Dietary phase Participants will ingest a low-oxalate (<60 mg/day), normal calcium (1000 mg/day) fixed diet for 4 consecutive days, collect three 24-hr urines after 1 day of dietary equilibration and have a fasted blood draw on day 5.

• Study Type: Interventional
• Enrollment (Actual): 58
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Alabama
    • Birmingham, Alabama, United States, 35294
      • University of Alabama at Birmingham

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 15 years to 61 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria

Age 19-70 yrs Body Mass Index > 18.5 kg/m2 Normal fasting serum electrolytes on comprehensive metabolic profile Willing to ingest fixed diets

Exclusion Criteria

Chronic Kidney Disease, estimated glomerular filtration rate < 60 ml/mn/1.73m2 Primary hyperoxaluria Liver, endocrine or renal diseases 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, Cystinuria, Uric acid stone former, Nephrotic syndrome, Sarcoidosis, Renal tubular acidosis, Primary hyperparathyroidism, Neurogenic bladder, Urinary diversion 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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Normal Individuals; Normal individuals: no prior history of kidney stones	Dietary supplement: Normal Individuals; Controlled Dietary phase: Low oxalate fixed diet 4 days of fixed normal calorie diet with low oxalate (< 60 mg/day), normal calcium (800-1200 mg/day)

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Urinary Oxalate Excretion	Mean Urinary oxalate excretion from three 24 hour urine collections on the fixed diet (mg/day)	3 days on the fixed diet

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Urinary Glycolate Excretion	mean of three 24-hr urinary glycolate collected on the fixed diet (mg/day)	3 days on fixed diet
Urinary Creatinine Excretion	mean of there 24hr urinary creatinine excretion on the fixed diet ( g/day)	3 days on the fixed diet

Collaborators and Investigators

• Sponsor: University of Alabama at Birmingham
• Collaborators: National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK); National Institutes of Health (NIH)
• Investigators: Principal Investigator: Kyle D Wood, MD, University of Alabama at Birmingham

Study record dates

Study Major Dates

• Study Start (Actual): January 1, 2013
• Primary Completion (Actual): July 1, 2023
• Study Completion (Actual): July 31, 2024

Study Registration Dates

• First Submitted: December 26, 2018
• First Submitted That Met QC Criteria: January 16, 2019
• First Posted (Actual): January 17, 2019

Study Record Updates

• Last Update Posted (Actual): June 1, 2026
• Last Update Submitted That Met QC Criteria: May 28, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: obesity; kidney stones; oxalate
• Additional Relevant MeSH Terms: Urogenital Diseases; Nutrition Disorders; Male Urogenital Diseases; Calculi; Pathological Conditions, Anatomical; Kidney Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Urolithiasis; Urinary Calculi; Overnutrition; Body Weight; Overweight; Nephrolithiasis; Pathological Conditions, Signs and Symptoms; Nutritional and Metabolic Diseases; Signs and Symptoms; Kidney Calculi; Obesity; Physiological Effects of Drugs; Calcium-Regulating Hormones and Agents; Calcium
• Other Study ID Numbers: IRB130502007-OBE; 1K08DK115833-01A1 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No