FGF23 and Cognitive impairment: Notably, toxins that have been linked to an increased risk of cognitive impairment in CKD patients include phosphate, para-cresyl sulfate (PCS), indoxyl sulfate (IS), and fibroblast growth factor 23 (FGF23) [43], as well as neuropeptide Y, a polypeptide implicated in some neurodegenerative and neuroimmune disorders [44] and present in high levels in CKD patients [45].