Vitamin D, in the form of supplements or its activated analogues, is a standard of care in the treatment of chronic kidney disease–mineral and bone disorder (CKD-MBD), the systemic complication of bone disease, biochemical abnormalities, and extraskeletal calcification present in many of the>800 million people worldwide with CKD.1 Reasons long touted for vitamin D use in this population include that it may improve high-turnover bone disease,2 restore systemic pleiotropic benefits of vitamin D,3 reduce vascular osteogenesis at low doses,4 and temper rising concentrations of parathyroid hormone (PTH), which has been consistently linked to mortality and poor outcomes in observational studies.