FGF23 and Marchiafava-Bignami disease: At the G5 stage of CKD, CKD-MBD is mainly characterized by hypocalcemia, hyperphosphatemia, deficiency of 25-hydroxyvitamin D (25(OH)vitD) and 1,25-dihydroxyvitamin D(1,25(OH)vitD), hyperparathyroidism, and an increased fibroblast growth factor 23 (FGF23) level, accompanied with higher risks of cardiovascular disease, fractures, and death [2–4].