Chronic kidney disease/bone and mineral metabolism: the imperfect storm.

As kidney function declines, chronic kidney disease (CKD) becomes an increasingly systemic disorder. Most patients with CKD eventually develop subclinical or clinical abnormalities in bone and mineral metabolism. Recent observational and basic scientific studies have led to a new emphasis on the changes in phosphorus and calcium metabolism, parathyroid hormone, and vitamin D that lead to this complex systemic bone/mineral disorder (CKD/BMD). At the center of the disorder are relationships among all 4 factors that conspire to create a perfect storm, leading to secondary hyperparathyroidism (SHPT). Some key current issues that are reviewed here are as follows: (1) factors promoting SHPT, (2) the role of fibroblast growth factor-23 in CKD/BMD, (3) molecular mechanisms of SHPT, (4) mechanisms of vascular calcification, and (5) medical management of the disorder, including calcimimetics. Current therapies directed at correcting the primary abnormalities (ie, improve conditions to an imperfect storm) and minimizing the consequences of CKD/BMD are discussed.