Serum Concentration of p-Cresol and Indoxyl Sulfate in Elderly Hemodialysis Patients

Abstract

Background: Uremic syndrome is a consequence of the retention of uremic solutes. 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 serum levels of IS and p-cresol in elderly dialysis patients. Methods: One hundred two stable hemodialysis patients from a single medical center were selected and divided into elderly and nonelderly groups based on the age at which they started dialysis. The elderly patients were also classified into diabetic and nondiabetic groups. The serum levels of total and free p-cresol and IS were measured using ultra performance liquid chromatography. Biochemical data were also collected concurrently. Results: There were no statistical differences in biochemistry or in serum IS and p-cresol levels (total or free) between the elderly and nonelderly groups. For the elderly dialysis patients, total IS was positively related to age (r=−0.31, p<0.01); calcium level (r=0.297, p<0.05); and creatinine (r=0.44, p<0.01). Total p-cresol had a significant relationship with diabetes (r=0.30, p<0.01). Neither total nor free p-cresol was associated with any biochemical result. The elderly diabetic group had significantly higher serum total p-cresol level (p=0.035) when compared with the nondiabetic group. Conclusion: This study shows that the elderly hemodialysis patients do not have higher serum p-cresol and IS levels. Diabetes was associated with serum total p-cresol level in elderly dialysis patients.

Keywords

• elderly
• hemodialysis
• indoxyl sulfate
• p-cresol
• protein-bound uremic toxin