CI RAMOS1,2, RG ARMANI1, ME CANZIANNI1, LS NAKAO3, KL CAMPBELL2, L CUPPARI1
1Federal University of São Paulo, Brazil; 2Faculty of Health Sciences and Medicine, Bond University, Queensland; 3Federal University of Paraná, Brazil.
Aim: To investigate the relationship between bowel habits and serum p-cresyl sulfate (PCS) in non-dialysis dependent chronic kidney disease patients (NDD-CKD).
Background: Constipation is prevalent in CKD and can contribute with uremic toxicity by reducing the excretion of waste products thought faecal route. PCS is a toxin derived from the metabolism of gut microbiota, and its serum concentration is increased in conditions of reduced excretion (CKD) and unbalanced gut environment; which can be influenced by the bowel habit.
Methods: This is a cross-sectional analysis of 43 non-diabetic NDD-CKD patients [58% men, 59.0±13.5 years old; glomerular filtration rate (eGFR) 21.3±7.9ml/min/1.73m2]. Bowel habit was evaluated by 7-day Bristol Stool scale (BSS); with an average score <3 indicating a tendency toward constipation with hard consistency of stools and/or low frequency of evacuation, than scores ≥3. Dietary intake was assessed by 3-day food record. Serum PCS was determined by high performance liquid chromatography.
Results: Fourteen patients (32.6%) had a tendency toward constipation with BSS score <3. The groups were homogeneous in regards to gender, age, eGFR and dietary intake. However, the BSS score ≤3 exhibited higher PCS than the more positive bowel habit group scoring ≥3 (63.8 [46.1–106.5mg/L] vs 35.0 [25.0–61.6mg/L], respectively; p=0.01). The effect of bowel habits on serum PCS was independent of eGFR and dietary protein-fibre ratio [B=0.43mg/L, 95% confidence interval: 0.06 – 0.080mg/L; p=0.02].
Conclusions: A compromised bowel habit evaluated by BSS was associated with higher PCS in non-diabetic NDD-CKD patients, independent of eGFR and dietary intake. Improvements in Bristol Stool scale to reduce serum PCS should be explored by interventional studies.