The goal of this clinical trial study is to test if patients with idiopathic calcium oxalate kidney stones have an increased absorption of dietary oxalate, which would lead to increased urinary excretion of oxalate.
The study will recruit adult patients with a history of calcium oxalate kidney stones and healthy volunteers without kidney stones.
Participants will
* ingest fixed diets containing low and moderately high amounts of oxalate for 5 days at a time * ingest a soluble form of oxalate and sugar preparations to test gut permeability * collect urine, blood, stool and breath sample during the fixed diets and the soluble oxalate test
age 18-70 yrs
Body Mass Index > 18.5 kg/m2
Normal fasting serum electrolytes on comprehensive metabolic profile
Willing to ingest fixed diets
Chronic Kidney Disease stage 4-5
Primary hyperoxaluria, Enteric (secondary) hyperoxaluria
Liver, bowel, endocrine or renal diseases (other than idiopathic Calcium Oxalate kidney stones) 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, Celiac disease, Cystinuria, Uric acid stone former, Nephrotic syndrome, Sarcoidosis, Renal tubular acidosis, Primary hyperparathyroidism, Neurogenic bladder, Urinary diversion, Chronic diarrhea, Bariatric surgery, Inflammatory bowel disease
Pregnancy or breast-feeding
Parallel
Low-oxalate diet
Dietary supplement4 days of fixed eucaloric diet with low oxalate (\<60 mg/day), normal calcium content (600-1000 mg/day)
High-oxalate diet
Dietary supplement4 days of fixed eucaloric diet with moderately high oxalate (250-300 mg/day), normal calcium content (600-1000 mg/day)
soluble oxalate gut absorption test
Other interventionOral ingestion of 13C2-oxalate and sucralose.
Net Gastrointestinal absorption of food-bound oxalate
difference between 24-hour urinary oxalate excretion on the high oxalate diet and the low oxalate diet, normalized to the difference in dietary oxalate composition of the two diets (%)
Absorption of soluble 13C2-oxalate
Proportion of 13C2-oxalate recovered in urine to the amount orally ingested (%)
Estimated endogenous oxalate synthesis (oxalate mg/day)
24-hour urinary oxalate excretion on the low oxalate diet (mg/day)
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University of Alabama at Birmingham
Lead sponsor
University of Texas Southwestern Medical Center
Collaborator
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Collaborator
