Bowel Habits and the Association With Uremic Toxins in Non–Dialysis-Dependent Chronic Kidney Disease Patients

Objective The aim of this study is to evaluate the association between bowel habits and microbial-derived uremic toxins p-cresyl sulfate (PCS) and indoxyl sulfate (IS) in patients with non–dialysis-dependent chronic kidney disease (NDD-CKD). Design and Methods This is a cross-sectional analysis including 43 nondiabetic NDD-CKD patients (58% men; 59.0 ± 13.5 years; estimated glomerular filtration rate, 21.3 ± 7.9 mL/min/1.73 m 2 ). Bowel habit was assessed by the Bristol Stool Scale (BSS Results The frequency of constipation assessed by BSS and Rome III criteria was 33% (n = 14/43) and 35% (n = 15/43), respectively. The BSS P  = .02; serum free PCS = 1.40 [1.00-1.97], P  = .05; urinary PCS = 1.78 [1.10-2.90], P P  = .09) and a significantly higher urinary PCS (β [95% CI]: 1.80 [1.11-2.94 μmol/24 h], P  = .02) was found in constipated participants. No effect of a compromised bowel habit (Rome III criteria or BSS) was found on IS. Conclusion Constipation may lead to production of PCS in nondiabetic NDD-CKD patients.