FGF-23 and vitamin D: don't shoot the messenger?

The discovery of fibroblast growth factor-23 (FGF-23) as a key regulator of phosphate and vitamin D metabolism has forced a rethink about the mineral and bone disorder of chronic kidney disease (CKD). FGF-23 powerfully predicts adverse cardiovascular outcomes in patients with CKD and an important question is whether treatment regimens should now be tailored to address FGF-23 levels in addition to those of calcium, phosphate, parathyroid hormone and vitamin D. Nevertheless, despite the known action of active vitamin D therapies to increase FGF-23, this should probably still form an important part of the management of patients with hyperparathyroidism and perhaps at low doses of essentially all patients with advanced renal disease.