[Vitamin D treatment--which analogs and when?].

Chronic kidney disease is associated with a decreased production of the active metabolite of vitamin D, 1 alpha,25-Dihydroxy-Vitamin D. This decrease has several consequences which are not only restricted to the bones. Indeed, vitamin D has multiple actions which are discussed in this review. Vitamin D substitution is considered early in the treatment of chronic kidney disease but uncertainties about the type of substitution remain. The role of vitamin D analogs are reviewed with emphasis on the comparison between calcitriol and paricalcitol.