Assessment of Endogenous Oxalate Synthesis

Purpose

This study aims to determine the daily rate of endogenous synthesis of oxalate using carbon 13 oxalate isotope tracer technique and a low-oxalate controlled diet.

Conditions

  • Healthy
  • Kidney Stone
  • Obesity

Eligibility

Eligible Ages
Between 18 Years and 75 Years
Eligible Genders
All
Accepts Healthy Volunteers
Yes

Inclusion Criteria

  • Mentally competent adults, able to read and comprehend the consent form - Body Mass Index (BMI) between 18.5 and 50 kg/m2 - Acceptable 24 hour urine collections (judged on screening) - for non-stone formers, good health as judged from a medical history, reported medications, and a complete blood metabolic profile, baseline urinary oxalate excretion < 40 mg/day - for kidney stone formers: first time or recurrent CaOx stone former with stone event within the prior 3 years. Composition of most recent stone (if known) > 50% calcium oxalate, without uric acid component.

Exclusion Criteria

  • History of any hepatic, bowel, or endocrine disease or other condition that may influence the absorption, transport or urine excretion of ions - Abnormal urine chemistries or blood metabolic profiles - Poor 24 hour urine collections completed during screening, judged by 24 hour urine creatinine excretion (indicative of not collecting all urine in the 24 hour period) - Pregnancy, intention to become pregnant in the near future, or lactation - Aged <18 or >75 years - BMI <18.5 or >50 kg/m2

Study Design

Phase
N/A
Study Type
Interventional
Allocation
N/A
Intervention Model
Sequential Assignment
Primary Purpose
Basic Science
Masking
None (Open Label)

Arm Groups

ArmDescriptionAssigned Intervention
Experimental
Constant infusion of 13C2-oxalate 		Subjects who have passed screening, will consume a low-oxalate, normal calcium controlled diet for 5 days total. On Days 3 and 4, subjects will collect two 24-hour urines. On Day 5, they will receive a carbon 13 oxalate infusion which will occur at a constant rate for 6 hours, in the fasted state, following a priming dose. Hourly urine and twice hourly blood samples will be collected during the 6 hours. Meals will be resumed at the end of the infusion and timed urine collections will take place at home until the next day. A DXA scan will be performed to assess body composition at another date.
  • Dietary Supplement: Low-oxalate controlled diet
    Participants will consume a diet that is controlled in its contents of protein, carbohydrates, fat, calcium, oxalate, vitamin C and sodium for 5 days. Participants will be asked not to take any dietary supplements, exercise strenuously, or consume food or drink that is not provided to them.
  • Other: Primed, continuous intravenous infusion of 13C2-oxalate
    Participants will receive a continuous intravenous administration of carbon-13 oxalate, a naturally occurring form of oxalate, over the course of several hours until steady-state is achieved, using an IV catheter, while remaining fasting.

Recruiting Locations

University of Alabama at Birmingham
Birmingham, Alabama 35294
Contact:
Sonia Fargue, PhD
205-975-6932
kidneystone@uabmc.edu

More Details

Status
Recruiting
Sponsor
University of Alabama at Birmingham

Study Contact

Sonia Fargue, PhD
205-9756932
kidneystone@uabmc.edu

Detailed Description

Urinary oxalate excretion is derived from both dietary sources and endogenous synthesis. This study will use low-oxalate controlled diet and intravenous infusion of the isotope tracer carbon 13 oxalate, timed with blood and urine collections, to determine the daily rate of endogenous oxalate synthesis in non-stone forming volunteers and in subjects with calcium oxalate kidney stones. A DXA scan will be used to assess body composition.