Use of vitamin D in chronic kidney disease patients.

Chronic kidney disease (CKD) has been recognized as a significant public health problem, with 20 million Americans, or 11% of the adult population, currently living with CKD. Life expectancy in patients with CKD is limited by the development of disturbances of mineral metabolism, which occurs in virtually all patients during the progression of their disease, and is associated with bone loss and fractures, cardiovascular disease, immune suppression, and increased mortality. As kidney disease develops, there is decreased functional renal mass and a reduction in renal 1alpha-hydroxylase activity and thus in renal production of calcitriol at very early CKD stages. Recently, a potentially important role of vitamin D receptor activation (VDRa) in the survival of patients undergoing dialysis has been suggested. Beyond the effect on parathyroid hormone suppression, the pleiotropic effect of vitamin D has been associated with improvement of cardiovascular risk factors, including increased renin activity, hypertension, inflammation, insulin resistance, diabetes, and albuminuria. However, the current K/DOQI and KDIGO recommendations limit the administration of VDRa agents for treatment of hyperparathyroidism only. The role of vitamin D administration in the different CKD stages will be discussed in this review.