PTH and Marchiafava-Bignami disease: CKD–MBD encompasses abnormalities of calcium and phosphate metabolism induced by the deregulation of parathyroid hormone (PTH), fibroblast growth factor 23 (FGF23) and vitamin D homeostasis that lead to renal osteodystrophy (ROD), a term used to describe the different patterns of skeletal abnormalities in patients with CKD and extra-osseous calcifications.