Associations among total p-cresylsulfate, indoxyl sulfate and hippuric acid levels with hemodialysis quality indicators in maintenance hemodialysis patients.

Background: Total p-cresylsulfate (PCS), indoxyl sulfate (IS) and hippuric acid (HA) are harmful uremic toxins known to be elevated in patients with uremia. Serum total PCS, IS and HA levels have been associated with coronary atherosclerosis, left ventricular hypertrophy, metabolic acidosis, neurological symptoms, and accelerated renal damage associated with chronic kidney disease; however, no study has examined the effect of total PCS, IS and HA on hemodialysis (HD) quality indicators. The aim of this study was to examine associations among total PCS, IS and HA with HD quality indicators in patients undergoing HD treatment.

Methods: This study included 264 consecutive patients at a single HD center who assessed using previously demonstrated HD quality indicators including anemia, bone-mineral metabolism, dialysis dose, cardiovascular risk, and middle molecule removal area. Serum HA was measured using a capillary electrophoresis method. Serum total PCS and IS concentrations were measured using an Ultra Performance LC System.

Results: Multiple regression analysis showed that sex, potassium, systolic blood pressure (SBP), average BP, β2-microglobulin, and creatinine were independently positively associated with IS level, and that age, total cholesterol, and estimated glomerular filtration rate (eGFR) was independently negatively associated with IS level. In addition, β2-microglobulin was independently positively associated with total PCS. Moreover, potassium, diastolic blood pressure, average BP, β2-microglobulin, dialysis vintage, and albumin were independently positively associated with HA level, and age, transferrin saturation, fasting glucose, and eGFR were independently negatively associated with HA level. When the patients were stratified by age and sex, serum IS and HA levels were still independently associated with some hemodialysis quality indicators. In addition, canonical correlation analysis also confirmed the relationship between uremic toxins (IS and HA) and HD quality indicators (potassium, β2-microglobulin, average BP, creatinine, and eGFR).

Conclusion: This study demonstrated that uremic toxins (IS and HA) and HD quality indicators (potassium, β2-microglobulin, average BP, creatinine, and eGFR) constructs were correlated with each other, and that there were sex and age differences in these associations among maintenance HD patients.