FGF23 and Hypercalciuria: Hypercalciuria is the most common metabolic abnormality found in nearly 50% of calcium stone formers and characterized as a systemic abnormality of calcium homeostasis in which a dysregulation of calcium transport takes place in the kidneys, intestine, and bones, under influence of genetics, diet, and hormones, such as parathyroid hormone (PTH), fibroblast growth factor-23 (FGF-23), and the active form of vitamin D3, 1,25-dihydroxyvitamin-D3 (1,25(OH)2D3) [1,2,3].