FGF23 and secondary hyperparathyroidism: Other consequences of hyperphosphatemia are high levels of fibroblast growth factor 23 (FGF23), which is a hormone involved in phosphate and vitamin D regulation [8] and disruption of bone metabolism, leading to secondary hyperparathyroidism, renal osteodystrophy, and metabolic bone disease (CKD-MBD) [9].