The serum levels of P-cresol and Indoxyl sulfate in different hemodialysis vintage

Abstract

Indoxyl sulfate (IS) and para-cresol (p-cresol) belong to the group of protein-bound uremic toxins that are poorly cleared by dialysis and are associated with poor clinical outcomes. The goal of our study was to evaluate the relationship between dialysis time and serum levels of IS and p-cresol in hemodialysis (HD) patients. Our study enrolled 96 stable HD patients who were categorized into 8 subgroups on the basis of the duration for which they received dialysis within a period of 1 year. Patients with acute infection, malignancy or those who were younger than 18 years of age were excluded. Serum levels of total and free p-cresol and indoxyl sulfate were measured using ultra performance liquid chromatography (UPLC). Biochemical data was also collected concurrently. In our study, we found that only unbound IS and total IS were significantly and positively correlated with the dialysis time in HD patients by trend analysis (p= 0.020 and p=0.007, respectively). Other independent variables, including the levels of unbound p-cresol, total p-cresol, hemoglobin, highly sensitive C-reactive protein (CRP), Kt/V and albumin, did not show significant correlation with the length of HD treatment. Our results inferred that patients undergoing longer hemodialsysis may lead to higher serum levels of IS. Key words: Hemodialysis time, indoxyl sulfate, p-cresol, p-cresyl sulfate and protein-bound uremic toxin.