Nonclassic Actions of Vitamin D

CONTEXT: Vitamin D receptors are found in most tissues, not just those participating in the classic actions of vitamin D such as bone, gut, and kidney. These nonclassic tissues are therefore potential targets for the active metabolite of vitamin D, 1,25(OH)(2)D. Furthermore, many of these tissues also contain the enzyme CYP27B1 capable of producing 1,25(OH)(2)D from the circulating form of vitamin D. This review was intended to highlight the actions of 1,25(OH)(2)D in several of these tissues but starts with a review of vitamin D production, metabolism, and molecular mechanism. EVIDENCE ACQUISITION: Medline was searched for articles describing actions of 1,25(OH)(2)D on parathyroid hormone and insulin…