[ Summary ] |
Phosphate is an essential nutrient for biological activity. Serum phosphate levels are maintained by intestinal absorption and renal excretion. This precise system is mainly regulated by PTH, 1,25(OH)2D3 and FGF23. PTH and FGF23 decrease serum phosphate levels by inhibition of renal phosphate reabsorption. 1,25(OH)2D3 increases serum phosphate concentration through acceleration of intestinal phosphate absorption. Simultaneously, FGF23 suppresses both 1,25(OH)2D3 synthesis and PTH secretion, as well as stimulated 1,25(OH)2D3 resolution. On the other hand, PTH stimulates skeletal FGF23 production and renal 1,25(OH)2D3 synthesis. In addition, 1,25(OH)2D3 can suppress parathyroid PTH synthesis and skeletal FGF23 production. These three phosphate regulating hormones precisely maintain the phosphate regulatory system. These hormones work in concert as well as independently. |