The Role of P-cresol and Related Protein Fermentation Metabolites in Chronic Kidney Disease Patients

Chronic Kidney Disease

chronic kidney disease, cardiovascular disease, risk stratification

Study on the natural history of uremic retention solutes in patients with mild-to-moderate chronic kidney disease

Protein-bound uremic retention solutes are increasingly recognized to play a role in the pathophysiology of the uremic syndrome. Numerous in vitro findings are indicative for their implication in the biochemical and physiological changes of uremia. Several of these protein-bound retention solutes originate from bacterial protein fermentation in the colon. p-cresyl sulfate, a fermentation metabolite of the amino acid tyrosine, is considered a prototype of this group of uremic solutes. The protein binding of this molecule was shown to be about 90% in end-stage renal disease patients. Several data have suggested that p-cresol plays a role in the immunodeficiency of uremia. Recently, a link between the molecule and endothelial dysfunction has been demonstrated. Also other members of the class of protein-bound solutes have been found to be associated with immune dysfunction, endothelial cell dysfunction and, closely related to the latter, oxidative stress. Free serum levels of p-cresol were shown to be greater in stage 5 chronic kidney disease (CKD) patients treated with hemodialysis (HD) hospitalized for infectious disease. Furthermore, a positive relationship was found between serum total p-cresol level and a uremic symptom score in patients treated with peritoneal dialysis (PD), whereas a correlation with small water-soluble solutes and the middle molecule β2-microglobulin was absent. A recent prospective observational study in stage 5 CKD patients treated with conventional HD (3 x 4 hours per week) indicated that the accumulation of p-cresol is a risk factor for overall mortality. Data on the serum concentrations of p-cresol in chronic kidney disease patients are lacking. The investigators hypothesise that the serum concentration of p-cresol is an independent predictor of progression to end stage renal disease and is an independent predictor for cardiovascular disease.

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