FGF23 and chronic kidney disease: The term bone mineral disorder in CKD (CKD-MBD) describes one or a combination of the following three components: (i) Abnormalities of calcium, phosphorus, PTH, FGF23 and vitamin D metabolisms; (ii) Bone abnormalities (short stature, reduced mineralization and increased risk of fractures); (iii) Extraskeletal calcification [80].