Chronic kidney disease is associated with the accumulation of various metabolites, i.e., uremic retention solutes. Evidence is mounting that the colonic microbiome contributes substantially to these uremic retention solutes. Indoxyl sulfate and p-cresyl sulfate are among the most extensively studied gut microbial metabolites, and are associated with cardiovascular disease, chronic kidney disease progression and overall mortality. Indirect findings suggest that chronic kidney disease influences the colonic microbial metabolism with higher p-cresyl sulfate urinary excretion rates at more advanced renal disease. Therefore, this study aims to elucidate the influence of renal dysfunction on microbial metabolism and to test the hypothesis that chronic kidney disease patients carry a different fecal metabolite profile.

Inclusion Criteria:

• Age ≥ 18 and ≤ 95 years
• Treatment with renal replacement therapy, i.e. hemo- or peritoneal dialysis for more than 3 months
• Written informed consent

Exclusion Criteria:

• History of organic gastro-intestinal disease (e.g., inflammatory bowel disease, malignancy)
• History of colonic surgery
• Recipient of a renal or other solid organ transplant
• Use of pre-/pro-/syn- or antibiotics in preceding 4 weeks

Patients treated with renal replacement therapy, i.e. hemo- or peritoneal dialysis for more than 3 months