SOST and chronic kidney disease: In patients with early CKD (stages 1–2), the serum concentration of Wnt signaling inhibitors, such as DKK1 (Dickkopf-1), SOST (sclerostin), and sFRP (secreted frizzled-related proteins), increases because of the release from osteocyte or extraosseous-calcifying tissue and the decrease in renal excretion [17].