Dietary oxalate absorption and microbiome diversity in patients with nephrolithiasis and hyperoxaluria: a stable isotope technique.

Recruitment & Eligibility

Status: Recruiting

Sex: Not specified

Target Recruitment: 60

Inclusion Criteria

For this study, we identify four different groups of participants:
Group 1: patients with primary hyperoxaluria.
Group 2: patients with secondary or unspecified hyperoxaluria
Group 3: patients with idiopathic calcium oxalate kidney stones disease.
Group 4: control group of healthy volunteers.

Inclusion criteria primary hyperoxaluria (group 1):
- Age 16 - 60 years
- Diagnosed with primary hyperoxaluria (type 1, 2 or 3), confirmed by genetic
testing.

Inclusion criteria secondary or unspecified hyperoxaluria (group 2):
- Age 16 - 60 years
- Diagnosed with secondary hyperoxaluria, confirmed by: hyperoxaluria (defined
as > 0.5 mmol/1.73m2/day oxalate in 24-hours urine) and confirmed diagnosis of
a disease as underlying secondary enteral cause of hyperoxaluria.
- Diagnosed with unspecified hyperoxaluria.

Inclusion criteria CaOx stone formers (group 3):
- Age 16 - 60 years
- Recurrent calcium oxalate stones

Inclusion criteria healthy volunteers (group 4):
- Age 16 - 60 years
- Good health, no background of nephrolithiasis, kidney or gastrointestinal
disease.

Exclusion Criteria

- eGFR <30 ml/min/1.73m2
- Use of drugs affecting the gastrointestinal microbiome
- Gastro-intestinal or systemic diseases known to affect microbiome (causes of
secondary hyperoxaluria excluded)

Study & Design

Study Type: Observational non invasive

Study Design: Not specified

Primary Outcome Measures

Name	Time	Method
<p>1. To quantify dietary oxalate absorption from the gastrointestinal tract in<br /><br>patients with idiopathic CaOx kidney stones, primary hyperoxaluria, and<br /><br>secondary hyperoxaluria compared to healthy volunteers, by administering<br /><br>labelled oxalate.<br /><br>2. To identify differences in the intestinal microbiome between these patient<br /><br>groups, by looking at the diversity and abundance of (oxalate degrading)<br /><br>bacteria. </p><br>

Secondary Outcome Measures

Name	Time	Method
<p>1. To identify differences in the intestinal metabolome by measuring volatile<br /><br>and non-volatile organic compounds in the faeces and measuring labelled CO2 in<br /><br>exhaled air.</p><br>