Indoxyl sulfate has a dominant role regarding the risks during different stages of chronic kidney disease
Abstract Background: Increased levels of uremic toxins and decreased antioxidant capacities have a significant impact on the progression of chronic kidney disease (CKD). However, it is unclear whether they interact with each other in order to mediate the damage of renal function. The purpose of this study was to determine whether uremic toxins [i.e., homocysteine and indoxyl sulfate (IS)] and glutathione-dependent antioxidant enzyme activities are dependently or independently associated with each other in affecting renal function during different stages of CKD patients.Methods: One hundred thirty-two patients diagnosed with CKD stage 1 to 5 participated in this cross-sectional study.Results: Patients who had reached an advanced CKD stage experienced a gradual increase in plasma uremic toxin levels, along with decreased glutathione peroxidase (GSH-Px) activities. Plasma homocysteine, cysteine and IS concentrations were positively associated with each other, but negatively correlated to GSH-Px activity levels after adjusting potential confounders in all CKD patients. Although plasma homocysteine, cysteine, IS and GSH-Px levels were significantly associated with renal function, only plasma IS levels still had a significant association with renal function after these parameters were simultaneously adjusted.Conclusions: IS plays a more dominant role than other factors in affecting renal function, where a higher IS concentration needs to be controlled in order to defer the progressive loss of renal function.