FGF23 and Marchiafava-Bignami disease: Although this accuracy may not be very high for FGF23 level to be used as a gold standard for identifying patients with a risk of vertebral fracture, FGF23 level together with the levels of other bone-metabolism-related markers and dual-energy X-ray absorptiometry will be a more useful tool than FGF23 level alone for evaluating CKD-MBD and the risk for fractures and for deciding medications for CKD patients to prevent fractures and progression of CKD-MBD.