Current opinion on the regulation of small intestinal magnesium absorption

Figure 3 Integrated magnesiotropic action of fibroblast growth factor-23 and parathyroid hormone. Parathyroid hormone (PTH) stimulates the bone resorption process, which increases plasma calcium (Ca²⁺), inorganic phosphate (P_i), and magnesium (Mg²⁺) levels. PTH stimulates the release of 1,25-dihydroxy vitamin D₃ (1,25(OH)₂D₃) to subsequently induce small-intestinal Ca²⁺ absorption. PTH also activates renal tubular Ca²⁺ and Mg²⁺ reabsorption. Plasma Pi and PTH trigger the release of fibroblast growth factor-23 (FGF-23) to abolish 1,25(OH)₂D₃-induced intestinal Ca²⁺ absorption. PTH and FGF-23 synergistically suppress small intestinal absorption of dietary Mg²⁺. PTH and FGF-23 induce urinary P_i excretion.