Pleiotropic Effects of Vitamin D in Kidney Disease

Vitamin D is metabolized in the liver and kidneys and then converted to the active form, 1.25-dihydroxyvitamin D [1.25(OH)2D]. Chronic kidney disease patients usually lack both 25-hydroxyvitamin D [25(OH)D] and 1.25(OH)2D due to impaired renal function and 1α-hydroxylase deficiency. Chronic kidney disease patients have a high incidence of cardiovascular and infectious morbidities. Increasing evidence indicates a relationship between vitamin D deficiency and cardiovascular and infectious mortality risks. Vitamin D may have significant biological effects beyond its traditional roles on mineral and bone metabolism. Many extrarenal cells have the capability to produce local active 1.25(OH)2D in an intracrine or paracrine fashion. Vitamin D has a significant association with nonskeletal diseases, such as immunodeficiency, metabolic syndrome, insulin resistance, diabetes, hyperlipidemia, cardiovascular disease, proteinuria, and acute kidney injury. This article aims to review and summarize the pleiotropic effects of vitamin D in patients with kidney disease, particularly the immunological, metabolic, cardiovascular, and renal effects