The goal of this clinical trial study is to test if patients with idiopathic calcium oxalate kidney stones have an increased production of oxalate by the body, 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 amounts of oxalate for 5 days ingest a soluble form of glycolate and vitamin C collect urine, blood, stool during the dietary and oral dosing portions of the study and also collect breath sample during the oral glycolate test
age 18-80 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 and glycolate dosing
Dietary supplementLow-oxalate diet 4 days of fixed eucaloric diet with low oxalate (\<60 mg/day), normal calcium content (600-1000 mg/day)
Oral glycolate dosing
Dietary supplementOral 13C-glycolate dosing (0.5 mg/kg)
Oral 13C- ascorbic acid dosing
Dietary supplementOral 13C- ascorbic acid dosing (0.75 mg/kg)
Estimated endogenous oxalate synthesis (oxalate mg/day)
Basal rate of endogenous oxalate synthesis estimated by repeat fasted hourly urine collections (mg/day)
24-hour urinary oxalate excretion on low oxalate diet
mean 24-hour urinary oxalate excretion on the low oxalate diet (mg/day)
contribution of ascorbic acid breakdown to urinary oxalate excretion
contribution of ascorbic acid breakdown to oxalate synthesis (%)
Contribution of glycolate metabolism to urinary oxalate
Proportion of 13C-glycolate orally dosed that is metabolized to urinary 13C-oxalate in the fasted stated (%)
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University of Alabama at Birmingham
Lead sponsor
University of Texas, Southwestern Medical Center at Dallas
Collaborator
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Collaborator
