Osteoblasts express components necessary for coordinating mineralization of ECM and phosphate handling by the kidney. FGF-23 secreted from osteoblasts under the control of PHEX and possibly G_sα-dependent pathways has systemic actions to regulate renal phosphate handling as well as potential autocrine effects to regulate osteoblast-mediated bone mineralization. The LRP-Wnt signaling pathway in osteoblasts regulates bone mass and, in conjunction with PHEX and FGF-23, may also participate in coordinating renal phosphate conservation to meet the needs of osteoblast-mediated mineralization.