PTH and chronic kidney disease: Molecules previously shown to be involved in VC in CKD, including fibroblast growth factor 23, sclerostin, parathyroid hormone, bone-specific alkaline phosphatase, matrix Gla protein, osteocalcin, and osteoprotegerin, have larger molecular weight and express more specific pathophysiological processes (29–34) compared to the metabolites shown in Figure 4.