Serum Indoxyl Sulfate as a Potential Biomarker of Peripheral Arterial Stiffness in Patients with Non-Dialysis Chronic Kidney Disease Stages 3 to 5.

Indoxyl sulfate (IS), which is a protein-bound uremic toxin, is involved in vascular dysfunction and cardiovascular risk in subjects with chronic kidney disease (CKD). However, its role in peripheral arterial stiffness (PAS) remains unclear. This cross-sectional study evaluated the relationship between IS and PAS in patients diagnosed with CKD stages 3 through 5 who are not undergoing dialysis. Patients with CKD from a single center were enrolled. High-performance liquid chromatography analyzed the serum IS levels. PAS was evaluated using brachial-ankle pulse wave velocity (baPWV). IS was independently associated with PAS (odds ratio [OR]: 1.389 for 1 μg/mL increase in IS, 95% confidence interval [CI]: 1.086-1.775, p = 0.009) in a multivariable analysis after adjustment for age, hypertension, diabetes mellitus, blood pressure, lipid profiles, renal function, albumin, and proteinuria. Moreover, the mean baPWV (p = 0.010), left baPWV (p = 0.009), and right baPWV (p = 0.015) levels significantly correlated with the log-transformed IS (log-IS) levels. The area under the receiver operating characteristic curve for serum IS as a predictor of PAS was determined to be 0.667 (95% CI: 0.580-0.754; p = 0.0002). IS was associated with PAS in non-dialysis CKD stages 3-5, suggesting that IS may be a possible vascular risk marker. Future studies should address the nature of the relationship between IS and vascular dysfunction and assess therapeutic strategies to reduce IS.