Overview
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.
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.
Eligibility
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