Gut Kidney Axis in Enteric Hyperoxaluria

40 subjects with a confirmed diagnosis of IBD or \>6 months post-RYGB with a diagnosed USD event or kidney stone on imaging within the past three years and 40 healthy controls will be administered a high oxalate diet on Days 0-3 and Days 21-24 with a washout period on Days 4-7 and will be administered 250mg sodium oxalate on Days 8-20, via prepared spinach, from Weil Cornell Medicine's Clinical and Translational Science Center. Subjects will partake in four stool collections, four 24-h urine collections, two blood collections, and four sets of colonic permeability testing.


Eligibility Criteria:
Inclusion Criteria:

In order to be eligible to participate in this study, an individual must meet all of the following criteria:

* Subjects \> 18 years and \< 80 years of age
* a confirmed diagnosis of IBD or \> 6 months post- RYGB, with a diagnosis USD event (renal colic with spontaneous stone passage, emergency room visits, or urological interventions) or have kidney stone on imaging (CT, MRI, or US) in the previous three years.
* We will include all racial and ethnic groups, and both men and women.

In order to be eligible in this study as a healthy control, an individual must meet all of the following criteria:

* Subjects \> 18 years and \< 80 years of age
* Healthy controls with no chronic diseases, not on any chronic medications, no history of GI pathology, or urinary stone disease (USD).
* We will include all racial and ethnic groups, and both men and women.

Exclusion Criteria:

An individual who meets any of the following criteria will be excluded from participation in this study:

* pregnant or nursing women and people with any medical, psychiatric, debilitating disease/disorder or social condition that, in the judgment of the investigator, would interfere with or serve as a contraindication to adherence to the study protocol, ability to give ICF or complete the protocol.
* subjects with total and partial colectomy.
* subjects who received oral, intramuscular, or intravenous antibiotics within three months before screening.
* Patients with perianal disease usually receive recurrent antibiotics and, therefore, will be excluded from the study.
* patients with an ongoing symptomatic IBD flare or a flare within the previous three months
* patients with estimated glomerular filtration rates (eGFR) \< 60 ml/min/1.73 m2 calculated by the CKD-EPI equation measured anytime within the preceding year.

An individual who meets any of the following criteria will be excluded from participation in this study as a healthy control:

* pregnant or nursing women and people with any medical, psychiatric, debilitating disease/disorder or social condition that, in the judgment of the investigator, would interfere with or serve as a contraindication to adherence to the study protocol, ability to give ICF or complete the protocol.
* subjects with total and partial colectomy.
* subjects who received oral, intramuscular, or intravenous antibiotics within three months before screening.
* Patients with perianal disease usually receive recurrent antibiotics and, therefore, will be excluded from the study.
* patients with an ongoing symptomatic IBD flare or a flare within the previous three months
* patients with estimated glomerular filtration rates (eGFR) \< 60 ml/min/1.73 m2 calculated by the CKD-EPI equation measured anytime within the preceding year.