FGF23 and chronic kidney disease: On the level of the vasculature, IS, pCS, and indole-3-acetic acid, as well as other uremic toxins, have all been linked to endothelial inflammation and oxidative stress.232 Furthermore, multiple uremic toxins accumulating in CKD have been linked to reduced vascular relaxation, as shown for IS,241 advanced glycation end products, and FGF23.232