Effect of Oxalate and Urate Metabolism on CKD Evolution

Inclusion Criteria: * age \>18 years old, * CKD stage 1-4, * the patients did not take antibiotics and/or probiotics, lipid- and/or urate-lowering therapy for at least past 3 months or: * dialysis treatment for at least 3 months, * a stable clinical condition and adequately functioning arteriovenous fistula or peritoneal access, * a target level of Kt/V (≥ 1.4 for the HD patients and ≥1.7 for the PD patients). Exclusion Criteria: * hospitalization in the preceding 3 months, * previous history or actual diagnosis of peritonitis, anemia, systemic and malignant diseases, acute inflammation processes, immunosuppressive treatment and active hepatitis.