Assessment of Endogenous Oxalate Synthesis

Assessment of Endogenous Oxalate Synthesis

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.

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.

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)
• good health as judged from a medical history, reported medications, and a complete blood metabolic profile
• with or without history of calcium oxalate kidney stones

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 lower than 18 or greater than 75 years
• BMI lower than18.5 or greater than 50 kg/m2