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Constipation may lead to uremic toxins in patients with CKD
Constipation was associated with the production of the uremic toxin p-cresylsulfate — but not indoxyl sulfate — in patients with chronic kidney disease, according to a published study.
As Christiane Ishikawa Ramos, PhD, of the Universidade Federal de Sao Paul in Brazil, and colleagues wrote, constipation is common in patients with CKD and may lead to negative clinical outcomes due to the “deleterious effect of gut dysbiosis and the increased production of uremic toxins, including p-cresyl sulfate (PCS) and indoxyl sulfate (IS), to the cardiovascular and renal systems.”
To determine whether constipation was associated with the production of microbial-derived uremic toxins, researchers identified 43 patients without diabetes who had eGFR less than 45 mL/min/1.73 m2, but who were not on dialysis (mean eGFR, 21.3 mL/min/1.73m2). They then assessed participants’ bowel habits using the Bristol Stool Scale (with a score of less than 3 correlating to hard consistency of stools and/or low frequency of evacuation) and the Rome III questionnaire (which examines six constipation-related symptoms).
Among total patients, the frequency of constipation was 33% using the BSS and was 35% using the Rome III. Researchers found that, independent of renal function and dietary protein-fiber ratio, patients with a BSS score of less than 3 had higher production of PCS (serum total = 1.54; serum free = 1.40; urinary = 1.78). Constipation was also associated with a tendency for higher serum total PCS and higher urinary PCS when using Rome III criteria.
Researchers wrote that, although constipation is a potentially modifiable factor, dietary interventions are lacking. They argued one reason for this is that the first-line treatment — high fiber and fluid intake — may not be advisable for these patients due to the risk of potassium and fluid overload.
“Searching for an alternative approach to treat constipation, our group has previously found that after small daily doses of olive oil or flaxseed oil for 4 weeks, more than half of the participants were no longer classified as constipated according to the Rome III criteria,” they wrote.
They wrote interventional studies must be done to further explore the treatment of constipation and its impact on PCS. – by Melissa J. Webb
Disclosures: The authors report no relevant financial disclosures.