Fecal Microbiota Transplantation in Kidney Stone Patients

This open-label pilot study evaluates whether oral microbial transplant therapy can change urine factors associated with recurrent calcium-oxalate kidney stones. Adults with high urine calcium or high urine oxalate will receive antibiotic pretreatment followed by microbial capsules. Changes in 24-hour urine calcium and oxalate and treatment safety will be assessed.

Inclusion Criteria: * Age 18 years or older and younger than 70 years. * Recent urinary stone disease with at least 50% calcium-oxalate composition confirmed by stone analysis. * 24-hour urinary calcium \>225 mg/day or urinary oxalate \>40 mg/day. * Able to provide informed consent. * Willing to complete safety follow-up, study visits, 24-hour urine collections, and serial stool collections. * Not actively participating in another interventional urinary stone disease trial. * eGFR \>=60. Exclusion Criteria: * Three or more NIH-defined metabolic syndrome features. * Any autoimmune disease or inflammatory bowel disease. * Major gastrointestinal surgery within 3 months, excluding appendectomy or cholecystectomy; history of total colectomy or bariatric surgery. * Primary or secondary hyperparathyroidism or PTH outside 15-65 pg/mL. * Pancreatic enzyme replacement, ongoing dialysis, or eGFR \=2 dysphagia. * Active gastrointestinal infection, toxic megacolon, or small bowel ileus. * Life expectancy \=80 mg/day.