Indoxyl sulfate, homocysteine, and antioxidant capacities in patients at different stages of chronic kidney disease.

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BACKGROUND/OBJECTIVESIncreased levels of uremic toxins and decreased antioxidant capacity have a significant impact on the progression of chronic kidney disease (CKD). However, it remains unclear whether they interact with each other to mediate the damage of kidney function. The purpose of this study was to investigate whether uremic toxins (i.e., homocysteine and indoxyl sulfate [IS]), as well as glutathione-dependent antioxidant enzyme activities are dependently or independently associated with kidney function during different stages of CKD patients.SUBJECTS/METHODSOne hundred thirty-two patients diagnosed with CKD at stages 1 to 5 participated in this cross-sectional study.RESULTSPatients who had reached an advanced CKD stage experienced an increase in plasma uremic toxin levels, along with decreased glutathione peroxidase (GSH-Px) activity. Plasma homocysteine, cysteine, and IS concentrations were all positively associated with each other, but negatively correlated to GSH-Px activity levels after adjusting for potential confounders in all CKD patients. Although plasma homocysteine, cysteine, IS, and GSH-Px levels were significantly associated with kidney function, only plasma IS levels still had a significant association with kidney function after these parameters were simultaneously adjusted. In addition, plasma IS could interact with GSH-Px activity to be associated with kidney function.CONCLUSIONSIS plays a more dominant role than homocysteine and GSH-Px activity in relation to kidney function.